Printable Solar Cells Research Articles

Current State and Future Perspectives of Printable Organic and Perovskite Solar Cells.

Photovoltaic technology presents a sustainable solution to address the escalating global energy consumption and a reliable strategy for achieving net-zero carbon emissions by 2050. Emerging photovoltaic technologies, especially the printable organic and perovskite solar cells, have attracted extensive attention due to their rapidly transcending power conversion efficiencies and facile processability, providing great potential to revolutionize the global photovoltaic market. To accelerate these technologies to translate from the laboratory scale to the industrial level, it is critical to develop well-defined and scalable protocols to deposit high-quality thin films of photoactive and charge-transporting materials. Herein, the current state of printable organic and perovskite solar cells is summarized and the view regarding the challenges and prospects toward their commercialization is shared. Different printing techniques are first introduced to provide a correlation between material properties and printing mechanisms, and the optimization of ink formulation and film-formation during large-area deposition of different functional layers in devices are then discussed. Engineering perspectives are also discussed to analyze the criteria for module design. Finally, perspectives are provided regarding the future development of these solar cells toward practical commercialization. It is believed that this perspective will provide insight into the development of printable solar cells and other electronic devices.

Splitting Photons into Pair Photons to Design a High-Performance Printable Solar Cell

Splitting Photons into Pair Photons to Design a High-Performance Printable Solar Cell

Printable high-efficiency organic ionic photovoltaic materials discovered by high-throughput first-principle calculations.

Printable solar cells are promising for low cost and large-scale production. As the two main classes of printable solar cells, organic and perovskite solar cells show distinct advantages and apparent drawbacks. The latter stand as major obstacle toward their commercialization. It is amazing if the advantages of organic and perovskite solar cells are integrated since some of them are complementary. Here, we report ionic-type high-efficiency photovoltaic materials which achieve this goal. We explore 46,388 organic materials from the Crystallography Open Database by extensive quantum mechanical calculations. Through photovoltaic-functionality-directed materials screening, we identify 5 organic ionic-type photovoltaic materials. They show the merits of nontoxic, high dielectric constant (27.03), high theoretical efficiency (28.7%), and superior thermal stability. Our findings propose ionic-type photovoltaic materials, which may surpass traditional organic and perovskite materials and open the door to next-generation printable solar cells.

Transition Metal Salt Promoted, Green, and High‐Yield Synthesis of Silver Nanowires for Flexible Transparent Conductive Electrodes

AbstractSilver nanowires (AgNWs) have attracted considerable interest from both academia and industry owing to their excellent electrical, optical, and chemical properties. For large‐scale synthesis of AgNWs, the polyol method involving ethylene glycol, a toxic alcohol, has been widely used. We herein report on a facile, green, high yield, transition metal salt promoted, open atmosphere method for the synthesis of high quality AgNWs in a glycerol‐water mixture. We have shown that transition metal salts have a strong influence on the morphology of AgNWs. Importantly, in the presence of copper(II) chloride, AgNWs with a high aspect ratio of around 400 (length, 36 μm; diameter, 90 nm) were obtained. Additionally, for the first time, we have demonstrated AgNWs based flexible transparent conductive electrodes (TCEs) on poly(sodium 4‐styrenesulfonate) (PSS) treated polyethylene terephthalate (PET) substrate with a sheet resistance of 34 Ω/sq and transmittance of 91 % at 550 nm. The PSS layer on the PET substrate generated a highly hydrophilic surface, which boosts interaction of AgNWs with the PET surface. We envision that our results would play a significant role both in the synthesis of AgNWs with high aspect ratio and also in designing new rigid and flexible TCEs having high transmittance and low sheet resistance for applications especially in printable solar cells, organic light emitting diodes, and high performance flexible electronics.

Editorial for the special issue “Printable solar cells: From materials to devices”

Editorial for the special issue “Printable solar cells: From materials to devices”

Toward printable solar cells based on PbX colloidal quantum dot inks.

Lead chalcogenide (PbX, X = S, Se) colloidal quantum dots (CQDs) are promising solution-processed semiconductor materials for the construction of low-cost, large-area, and flexible solar cells. The properties of CQDs endow them with advantages in semi-conducting film deposition compared to other solution-processed photovoltaic materials, which is critical for the fabrication of efficient large-area solar cells towards industrialization. However, the development of large-area CQD solar cells is impeded by the conventional solid-state ligand exchange process, where the tedious processing with high expense is indispensable to facilitate charge transport of CQD films for photovoltaic applications. In the past several years, the rapid development of CQD inks has boosted the device performance and dramatically simplified the fabrication process. The CQD inks are compatible with most of the industrialized printing techniques, demonstrating potential in fabricating solar modules for commercialization. This article aims to review the recent advances in solar cells based on PbX CQD inks, including both lab-scale and large-area photovoltaic devices prepared from solution-phase ligand exchange (SPLE) as well as the recently invented "one-step" synthesis. We expect to draw attention to the enormous potential of CQD inks for developing high-efficiency and low-cost large-area photovoltaics.

Water Phase Synthesis Method of CuInS2 Nanoparticles and Its Application for Photovoltaic Device

CIS (CuInS2) is one of the most effective photovoltaic devices with high stability and efficiency, because of its suitable bandgap (1.5eV). Moreover, it does not contain toxic materials, such as Se, within its components. However, productivity and utilization of natural resources under the gas phase synthesis method is relatively low, since vaporizing temperature of elements is extremely different. Thus, it is required to develop a synthesis method of CIS solar cell materials within liquid phase.Here, we have already developed a synthesizing method of single phase and homogenous CI (CuIn) alloy nanoparticles in aqueous solution. In this method, the concentration of the metal complexes in the solution are calculated by using the critical stability constants, and the reduction reaction rate of both metal ions is also controlled. Synthesized CI nanoparticles were spin coted onto Mo/glass substrate and selenized, consequently it shows the photo voltaic effect. Thus, printable solar cells can be formed by using this method. The synthesizing method contains the selenization which is a sort of evaporation method, so it is not liquid process completely. To synthesize CIS solar cells without the selenization, we tried to sulfurize CI nanoparticles but CIS particles were not synthesized. It is difficult to sulfurize CI nanoparticles because they are stable and hard to react with sulfur ions, so it is necessary to synthesize from copper ions and indium ions to CuInS2 particles directly.However, nobody can synthesize CuInS2 particles in aqueous solution because there is a difference between the sulfurization reaction rate of copper and indium ions. If the sulfurization reaction rate of both metal ions is different, they are sulfurized independently to form their own sulfides, such as Cu2S or CuS and In2S3. It is necessary to control and approximate the sulfurization reaction rate of both metal ions for synthesis of CuInS2 particles. Here, in the sulfurization process, the sulfurization reaction rate is correlation with potential energy such as gibbs free energy (ΔG) or activation energy (Ea ). Hence, CuInS2 particles can be synthesized under the condition that the ΔG or Ea in the sulfurization reaction of copper and indium ions are approximated.To synthesize CuInS2 particles in aqueous solution, we tried to approximate the ΔG of the sulfurization reaction of copper and indium ions.By calculating ΔGCu2S and ΔGIn2S3 , we obtained the correlation of KIn and KCu and we were able to select appropriate complexing agents, so we tried to synthesize CuInS2 particles by using these reagents.XRD data indicates that several peaks with a dominant CuInS2 peak were observed. From the above results, it can be said that the synthesis of the precursor of CuInS2 particles in aqueous solution was successful because the Ea of the sulfurization process are approximated in both metal ions.In addition, it was found that the ΔG of copper and indium ions are approximated in the sulfurization system (Cu-In-IDA), so it is necessary to control and approximate both the ΔG and Ea for synthesis of CuInS2 particles in aqueous solution.Although the precursor of CuInS2 were synthesized in aqueous solution, the size and shape of the particles were not uniform. Therefore, for preventing degradation of conversion efficiency, it is needed to develop a technique for homogenizing the shape and the size of the particles.Detailed and another results will be introduced in our presentation. This work has been supported by the Grant-in-Aid for Scientific Research (B) (18H03416).

Machine learning property prediction for organic photovoltaic devices

Organic photovoltaic (OPV) materials are promising candidates for cheap, printable solar cells. However, there are a very large number of potential donors and acceptors, making selection of the best materials difficult. Here, we show that machine-learning approaches can leverage computationally expensive DFT calculations to estimate important OPV materials properties quickly and accurately. We generate quantitative relationships between simple and interpretable chemical signature and one-hot descriptors and OPV power conversion efficiency (PCE), open circuit potential (Voc), short circuit density (Jsc), highest occupied molecular orbital (HOMO) energy, lowest unoccupied molecular orbital (LUMO) energy, and the HOMO–LUMO gap. The most robust and predictive models could predict PCE (computed by DFT) with a standard error of ±0.5 for percentage PCE for both the training and test set. This model is useful for pre-screening potential donor and acceptor materials for OPV applications, accelerating design of these devices for green energy applications.

Printable CsPbI3 Perovskite Solar Cells with PCE of 19% via an Additive Strategy.

All-inorganic CsPbI3 holds promise for efficient tandem solar cells, but reported fabrication techniques are not transferrable to scalable manufacturing methods. Herein, printable CsPbI3 solar cells are reported, in which the charge transporting layers and photoactive layer are deposited by fast blade-coating at a low temperature (≤100 °C)in ambient conditions. High-quality CsPbI3 films are grown via introducing a low concentration of the multifunctional molecular additive Zn(C6 F5 )2 , which reconciles the conflict between air-flow-assisted fast drying and low-quality film including energy misalignment and trap formation. Material analysis reveals a preferential accumulation of the additive close to the perovskite/SnO2 interface and strong chemisorption on the perovskite surface, which leads to the formation of energy gradients and suppressed trap formation within the perovskite film, as well as a 150 meV improvement of the energetic alignment at the perovskite/SnO2 interface. The combined benefits translate into significant enhancement of the power conversion efficiency to 19% for printable solar cells. The devices without encapsulation degrade only by ≈2% after 700 h in air conditions.

Water Phase Synthesis Method of CuInS2 Nanoparticles and Its Application of Photovoltaic Device

CIS (CuInS2) is one of the most effective photovoltaic devices with high stability and efficiency, because of its suitable bandgap (1.5eV). Moreover, it does not contain toxic materials, such as Se, within its components. However, productivity and utilization of natural resources under the gas phase synthesis method is relatively low, since vaporizing temperature of elements is extremely different. Thus, it is required to develop a synthesis method of CIS solar cell materials within liquid phase.Here, we have already developed a synthesizing method of single phase and homogenous CI (CuIn) alloy nanoparticles in aqueous solution. In this method, the concentration of the metal complexes in the solution are calculated by using the critical stability constants, and the reduction reaction rate of both metal ions is also controlled. Synthesized CI nanoparticles were spin coted onto Mo/glass substrate and selenized, consequently it shows the photo voltaic effect. Thus, printable solar cells can be formed by using this method. The synthesizing method contains the selenization which is a sort of evaporation method, so it is not liquid process completely. To synthesize CIS solar cells without the selenization, we tried to sulfurize CI nanoparticles but CIS particles were not synthesized. It is difficult to sulfurize CI nanoparticles because they are stable and hard to react with sulfur ions, so it is necessary to synthesize from copper ions and indium ions to CuInS2 particles directly.However, nobody can synthesize CuInS2 particles in aqueous solution because there is a difference between the sulfurization reaction rate of copper and indium ions. If the sulfurization reaction rate of both metal ions is different, they are sulfurized independently to form their own sulfides, such as Cu2S or CuS and In2S3. It is necessary to control and approximate the sulfurization reaction rate of both metal ions for synthesis of CuInS2 particles. Here, in the sulfurization process, the sulfurization reaction rate is correlation with potential energy such as gibbs free energy (ΔG) or activation energy (Ea ). Hence, CuInS2 particles can be synthesized under the condition that the ΔG or Ea in the sulfurization reaction of copper and indium ions are approximated.To synthesize CuInS2 particles in aqueous solution, we tried to approximate the ΔG of the sulfurization reaction of copper and indium ions.By calculating ΔGCu2S and ΔGIn2S3 , we obtained the correlation of KIn and KCu and we were able to select appropriate complexing agents, so we tried to synthesize CuInS2 particles by using these reagents.XRD data indicates that several peaks with a dominant CuInS2 peak were observed. From the above results, it can be said that the synthesis of the precursor of CuInS2 particles in aqueous solution was successful because the Ea of the sulfurization process are approximated in both metal ions.In addition, it was found that the ΔG of copper and indium ions are approximated in the sulfurization system (Cu-In-IDA), so it is necessary to control and approximate both the ΔG and Ea for synthesis of CuInS2 particles in aqueous solution.Although the precursor of CuInS2 were synthesized in aqueous solution, the size and shape of the particles were not uniform. Therefore, for preventing degradation of conversion efficiency, it is needed to develop a technique for homogenizing the shape and the size of the particles.Detailed and another results will be introduced in our presentation. This work has been supported by the Grant-in-Aid for Scientific Research (B) (18H03416).

Vertically Aligned 2D/3D Pb–Sn Perovskites with Enhanced Charge Extraction and Suppressed Phase Segregation for Efficient Printable Solar Cells

The concept of mixed 2D/3D heterostructures has emerged as an effective method for improving the stability of lead halide perovskite solar cells, which has been, however, rarely reported in lead–ti...

Synthesis of CuInS2 Particles in Aqueous Solution for Printable Photovoltaic Device

CuInS2(CIS) is one of the most effective photovoltaic devices with high stability and efficiency, since the bandgap of CIS is 1.5eV while ideal band gap for solar cell is 1.4eV. Moreover, unlike Cu(In,Ga)Se2(CIGS), it does not contain toxic materials, such as Se. However, since vaporizing temperature of four elements (Cu, In, Ga, Se) is extremely different, productivity under the gas phase is relatively low, which read the large amount of waste of resources. Thus, it is required to develop a synthesis method of CIS solar cell materials within liquid phase. Here, we have already developed a synthesizing method of single phase and homogenous copper-indium(CI) alloy nanoparticles in aqueous solution. In this method, the concentration of the metal complexes in the solution are calculated by using the critical stability constants, and the reduction reaction rate of both metal ions is also controlled. Synthesized CI nanoparticles were spin coted onto Mo/glass substrate and selenized, consequently it shows the photo voltaic effect. Thus, printable solar cells can be formed by using this method. The synthesizing method contains the selenization which is a sort of evaporation method, so it is not liquid process completely. To synthesize CIS solar cells without the selenization, we tried to sulfurize CI nanoparticles but CIS particles were not synthesized. It is difficult to sulfurize CI nanoparticles because they are stable and hard to react with sulfur ions, so it is necessary to synthesize from copper ions and indium ions to CuInS2 particles directly. However, nobody can synthesize CuInS2 particles in aqueous solution because there is a difference between the sulfurization reaction rate of copper and indium ions. If the sulfurization reaction rate of both metal ions is different, they are sulfurized independently to form their own sulfides, such as Cu2S or CuS and In2S3. It is necessary to control and approximate the sulfurization reaction rate of both metal ions for synthesis of CuInS2 particles. Here, in the sulfurization process, the sulfurization reaction rate is correlation with potential energy such as gibbs free energy (ΔG) or activation energy (Ea ). Hence, CuInS2 particles can be synthesized under the condition that the ΔG or Ea in the sulfurization reaction of copper and indium ions are approximated. To synthesize CuInS2 particles in aqueous solution, we tried to approximate the ΔG of the sulfurization reaction of copper and indium ions. By calculating ΔGCu2S and ΔGIn2S3 , we obtained the correlation of KIn and KCu and we were able to select appropriate complexing agents, so we tried to synthesize CuInS2 particles by using these reagents. XRD data indicates that several peaks with a dominant CuInS2 peak were observed. From the above results, it can be said that the synthesis of the precursor of CuInS2 particles in aqueous solution was successful because the Ea of the sulfurization process are approximated in both metal ions. In addition, it was found that the ΔG of copper and indium ions are approximated in the sulfurization system (Cu-In-IDA), so it is necessary to control and approximate both the ΔG and Ea for synthesis of CuInS2 particles in aqueous solution. Although the precursor of CuInS2 were synthesized in aqueous solution, the size and shape of the particles were not uniform. Therefore, for preventing degradation of conversion efficiency, it is needed to develop a technique for homogenizing the shape and the size of the particles. Detailed and another results will be introduced in our presentation. This work has been supported by the Grant-in-Aid for Scientific Research (B) (18H03416).

Synthesis of CIS (Cu-In-S2) Solar Cell Nanoparticles By Controlling the Concentration of Metal Complexes in an Aqueous Solution

CuInS2(CIS) is one of the most effective photovoltaic devices with high stability and efficiency, since the bandgap of CIS is 1.5eV while ideal band gap for solar cell is 1.4eV. Moreover, unlike Cu(In,Ga)Se2(CIGS), it does not contain toxic materials, such as Se [1]. However, since vaporizing temperature of four elements (Cu, In, Ga, Se) is extremely different, productivity under the gas phase is relatively low, which read the large amount of waste of resources. Thus, it is required to develop a synthesis method of CIS solar cell materials within liquid phase. Here, we have already developed a synthesizing method of single phase and homogeneous Copper-Indium (CI) alloy nanoparticles in an aqueous solution [2]. In this method, the concentration ratio of the metal complexes in the solution are calculated by using the critical stability constants, and the reduction rate is also controlled. Synthesized CI nanoparticles were spin coated onto substrate and selenized, consequently it shows the photo voltaic effect with the conversion efficiency of c.a. 2.3%. Thus, printable solar cell can be formed by using this method. However, CIS2 nanoparticles were not synthesized until now, because of ligand exchange reaction between the complexing agents and Cu and In. Therefore, in this study, to prevent these undesirable reaction, the condition of Cu-In-complexing reagent(s) system were precisely controlled by using the calculation. By using these calculation results, CIS2 particles were tried to synthesized in an aqueous solution Results of calculation indicated that iminodiacetic acid (IDA) was appropriate complexing reagent. In the ternary system of Cu-In-IDA, it was calculated that the Copper comlexes and Indium complexes can be restricted to homogenized species, [(Cu2+)(IDA)] (pH3) and [(In3+)(IDA)2] (pH3) under the condition that the total molar concentration of Copper and Indium ions were 5 mM, respectively. Based on this calculation, a solution under the above condition was prepared, and both metal complexes were tried to co-sulfurize. As a results, particles with amorphous like morphology were synthesized. Therefore, in order to improve the crystallinity, the particles were heated for 30 min at 500 °C under N2 atmosphere. XRD results of heat treated samples indicated that several peaks with a dominant CIS2 peak were observed. Thus, it can be said that CIS2 nanoparticles were successfully synthesized in an aqueous solution, without undesirable ligand exchange reaction during reaction. These results indicated that homogenize metal complexes system of Cu-In-IDA are essential for the synthesis of CIS2 particles. In our presentation, detailed and another results will be introduced. This work has been supported by the Grant-in-Aid for Scientific Research (B) (18H03416). [1]Recent Development of Thin Film Compound Semiconductor Photovoltaic Cells, Wada, Publication of CMC, 2007 [2] Aqueous Phase Synthesis of CuIn Alloy Nanoparticles and Their Application for a CIS (CuInSe2)-Based Printable Solar Battery, Hideyuki Takahashi, Hironari Fujiki, Shun Yokoyama, Takayuki Kai, Kazuyuki Tohji, nanomaterials, 2018, 8, 221

Effects of thiourea on the perovskite crystallization for fully printable solar cells

Fully printable HTL free perovskite solar cells (PSCs) are the most attractive candidates for large scale production, due to their low cost and high stability. In this kind of PSCs, perovskite precursor solutions are dropped on the three layer mesoscopic scaffolds, so it is important to improve the crystallinity as well as the penetrability into the mesoscopic scaffolds. Thiourea that has two NH2 groups and one S-donor can form hydrogen bond with the perovskite crystals or lewis acid-base adducts to retard the growth of perovskite crystals. In this work, it is found that thiourea facilitate the penetrability of perovskite precursor solution into the mesoscopic scaffolds and the crystallinity of perovskite crystals. It is suggested that such effects are associated with the cross-liker function and with the retarding function of thiourea. With adding thiourea into the perovskite precursor solution, electron transfer from perovskite crystals to FTO and the recombination resistance are enhanced, so that the performance of thiourea based device was improved from 10.20% (the pristine device) to 13.03%. Along with this, the thiourea can reduce iodine molecule to I− ion, so that perovskite films with thiourea have a higher stability than the pristine film.

Low temperature solution-derived TiO2-SnO2 bilayered electron transport layer for high performance perovskite solar cells

Planar lead halide perovskite solar cells have shown a promising application in the field of printable solar cells. However, high-performance planar perovskite solar cells typically need a high-temperature process to achieve crystallized titanium oxide films as the electron transport layers, which hinders their application in flexible plastic substrates. Here, we demonstrate a bilayered TiO2-SnO2 film as an excellent substitute for electron transport layer using a low temperature liquid phase method. The bilayered TiO2-SnO2 film exhibits efficient electron extraction and hole blocking ability even at a low processing temperature of 150 °C. The as-obtained solar cells exhibit a champion power conversion efficiency of 18.85% (Voc = 1.100 V, Jsc = 22.52 mA cm−2 and FF = 0.761) under one sun illumination, which is much higher than the devices based on individual SnO2 or TiO2 electron transport layers. The higher electron extraction driving force at the SnO2/perovskite interface and the stronger hole blocking ability due to the defect-free physical contact at the TiO2/FTO interface are suggested to be the main reasons for the improved device performance.

Enhanced efficiency and stability of fully air-processed TiO2 nanorods array based perovskite solar cell using commercial available CuSCN and carbon

In this study, commercial available inorganic p-semiconductor CuSCN and carbon was employed in replacing the expensive hole transport materials and noble metal electrode of the traditional perovskite solar cell, respectively. TiO2 compact layer and the mesoporous layer were also replaced by TiO2 nanorod arrays. The fully-air processed perovskite solar cells were easy to fabricate and demonstrated an enhanced efficiency and stability. The introduction of CuSCN improves the current density and the fill factor of the solar cell, thus leads to 29% increase in conversion efficiency. Intensity modulated photovoltage (IMVS) shows that the solar cell with CuSCN has a longer electron life time. Current attenuation curve shows that the current of the solar cell with CuSCN rises quicker and higher than that of the solar cell without CuSCN. The steady-state photoluminescence tests shows that the introduction of CuSCN layer enhances the separation of electrons and holes, thus reducing the recombination of electrons and holes. Electrochemical impedance spectroscopy (EIS) reveals that the solar cell with CuSCN has low transport resistance and high recombination resistance, thus leading to the slower electron recombination rates. In addition, study shows that the use of CuSCN and carbon displays high stability, and both kind of cells keep over 80% of the initial efficiency after 30 days without encapsulation. This method simplifies the perovskite solar cell fabrication process and opens a door toward the cheap, stable and printable solar cell.

Synthesis of CuInS2 Compound Solar Cell Nanoparticles in an Aqueous Solution By Controlling the Concentration of Metal Complexes

CuInS2(CIS) is one of the most effective photovoltaic devices for developing high stability and low cost solar cell. Bandgap of CIS is 1.5eV while ideal band gap for solar cell is 1.4eV, so CIS is suitable as solar cell materials. Moreover, unlike Cu(In,Ga)Se2(CIGS), it does not contain toxic materials, such as Se [1]. Until now, CIS solar cells have been synthesized by utilizing gas phase method. However, the gas phase evaporation process needs high energy consumption, high initial cost, and large amount loss of resources. For spreading the solar cells greatly, it is required to develop a method which can resolve the above problems, so it is necessary to synthesize CIS solar cells in liquid method. Here, we have already developed a synthesizing method of single phase and homogeneous Copper-Indium (CI) alloy nanoparticles in an aqueous solution. In this method, the concentration ratio of the metal complexes in the solution are calculated by using the critical stability constants, and the reduction reaction rate is also controlled. Synthesized CI nanoparticles were spin coated onto substrate and selenized, consequently it shows the photo voltaic effect. Thus, printable solar cell can be formed by using this method. However, CIS2 nanoparticles were not synthesized until now, because of ligand exchange reaction between the complexing agents and Cu and In. Therefore, in this study, to prevent these undesirable reaction, we tried to control the condition of Cu-In-complexing reagent(s) system precisely by using the calculation. By using these calculation results, CIS2 particles were tried to synthesized in an aqueous solution Results of calculation indicated that iminodiacetic acid (IDA) was appropriate complexing reagent. In the ternary system of Cu-In-IDA, it was calculated that the Copper comlexes and Indium complexes can be restricted to homogenized species, [(Cu2+)(IDA)] (pH3) and [(In3+)(IDA)2] (pH3) under the condition that the total molar concentration of Copper and Indium ions were 5 mM, respectively. Based on this calculation, a solution under the above condition was prepared, and both metal complexes were tried to co-sulfurize. As a results, particles with amorphous like morphology were obtained. Therefore, in order to improve the crystallinity, the particles were heated for 30 min at 500 °C under N2 atmosphere. XRD results of heat treated samples indicated that several peaks with a dominant CIS2 peak were observed. Thus, it can be said that CIS2 nanoparticles were successfully synthesized in an aqueous solution, without undesirable ligand exchange reaction during reaction. These results indicated that homogenize metal complexes system of Cu-In-IDA are essential for the synthesis of CIS2 particles. In our presentation, detailed and another results will be introduced. [1]Recent Development of Thin Film Compound Semiconductor Photovoltaic Cells, Wada, Publication of CMC, 2007

Extending lead-free hybrid photovoltaic materials to new structures: thiazolium, aminothiazolium and imidazolium iodobismuthates.

We report on the synthesis, crystal structures, optoelectronic properties and solar cell device studies of three novel organic-inorganic iodobismuthates - [C3H4NS]3[Bi2I9] ([TH]3[Bi2I9]), [C3H4N2]3[Bi2I9] ([IM]3[Bi2I9]) and [C3H5N2S][BiI4] ([AT][BiI4]) as lead-free light harvesters. [TH]3[Bi2I9] and [IM]3[Bi2I9] show zero-dimensional structures, whereas a one-dimensional edge-sharing chain structure of BiI6-octahedra was observed in [AT][BiI4], with interchain short II contacts also giving rise to the possibility of three-dimensional charge transport ability. Accordingly, greater energy dispersion in the band structure of [AT][BiI4] can be observed, and less contribution from the organic moities at the conduction band minimum in [AT][BiI4] than [TH]3[Bi2I9] have been confirmed by density functional theory calculations. Moreover, bandgap values are redshifted from 2.08 eV for [TH]3[Bi2I9] and 2.00 eV for [IM]3[Bi2I9] to 1.78 eV for [AT][BiI4], determined by UV-Vis reflectance spectroscopy. Power conversion efficiency of 0.47% has been achieved by using ([AT][BiI4]) as the light absorber in a hole-conductor-free, fully printable solar cell, with relatively good reproducibility. We also note the observation of a capacitance effect for the first time in a photovoltaic device with bismuth-based solar absorber, which may be related to the mesoporous carbon counter-electrode.

Fully-air processed Al-doped TiO2 nanorods perovskite solar cell using commercial available carbon instead of hole transport materials and noble metal electrode

Commercial available carbon paste was screen-printed instead of both the expensive hole transport materials (HTM) and noble metal electrode, and the fully-air processed perovskite solar cells based on Al-doped TiO2 nanorods arrays was fabricated and demonstrated the enhanced photo-electronic conversion efficiencies. Study show that aluminum doping changes the flat band of TiO2 nanorods and influence the open voltage. Electrochemical impedance spectroscopy shows that the resistance of the Al-doped TiO2 nanorods devices using commercial available carbon instead of HTM and noble metal electrode is higher than that of the un-doped devices, resulting in slower electron recombination rates, longer electron lifetimes and higher energy conversion efficiencies. Al-doped perovskite devices based on commercial available carbon achieve a PCE of 6.08% in ambient atmosphere, which is 19% higher than that of the undoped sample. This method greatly simplifies the process of the perovskite solar cell fabrication and opens a door toward the cheap and stable and printable solar cell based on commercial available carbon.

Simplified Architecture of a Fully Printable Perovskite Solar Cell Using a Thick Zirconia Layer

AbstractA fully printable, hole‐conductor‐free perovskite solar cell with a simple and low‐cost fabrication route and high stability is well placed for commercialization. We aim to simplify the fabrication process of these solar cells by replacing the mesoporous TiO2 (meso‐TiO2) layer with a thick ZrO2 layer. This new architecture required only three steps: screen‐printing first the compact TiO2 (c‐TiO2), second the mesoporous ZrO2 layer (for perovskite infiltration), and third the carbon electrode. To improve the solar cell performance of the architecture, the c‐TiO2 and ZrO2 printing process are optimized. After systematic optimization of these processes, we found that the double‐printing of the c‐TiO2 layer and an increase of the ZrO2 later thickness from 1.4 to 2.1 μm in the device structure gives an optimized efficiency of 9.69 %, which is comparable to that of standard carbon devices with meso‐TiO2. This method provides an approach to reduce the fabrication time and thermal budget for fully printable solar cells.