Layer For Perovskite Solar Cells Research Articles

The effect of different transition metal oxides on the characterization and photoluminescence properties of borosilicate glass ceramics containing nanosized anatase type-TiO2

In this study, crystallization of anatase type-TiO2 was achieved in the traditional borosilicate glasses (Na2O.B2O3.SiO2) for the first time. The effect of the TiO2 /Na2O ratio was studied to optimize the selected glass composition, also the effect of adding a definite amount of different transition metal oxides (TMO) was studied. The glasses were prepared via the conventional melt-quenching method. According to DSC results, heat treatment at 650 °C /10hrs was applied to convert the glasses into glass ceramics. XRD detected the crystallization of anatase, rutile, and cristobalite. A sample with a lower value of TiO2 /Na2O revealed a higher degree of crystallization of anatase than that with a higher value. Both Cr2O3 and NiO additions enhanced the crystallization of cristobalite; while additions of CoO, Fe2O3, V2O5, MnO, CuO or ZnO significantly enhanced the crystallization of anatase in the same order. The morphology of glass ceramic was observed by TEM and SEM, which revealed crystal size < 50 nm. The optical band gap was estimated from UV-Visible absorption spectra, it depicted a wide range of values (4.4–2.1 eV). PL spectra revealed emission colors varied from purple to blue color according to TMO and TiO2 /Na2O ratio. The obtained materials can be utilized as electron transport layers for perovskite solar cells.

Efficient modeling of double absorber layered structure in perovskite solar cells using machine learning techniques

This research article investigates the perovskite solar cells double absorber layer structure with 13 different absorber layer combinations. Our primary objective is to explore the potential for achieving high efficiency in perovskite solar cells. We present a double-layer structure for high efficiency, leveraging double absorber layers in perovskite solar cells expands spectral absorption and reduces thermalization losses, thereby enhancing power conversion efficiency and stability. Double absorber layer perovskite solar cells adaptability and integration potential further promise efficiency and reliability advancements. Through a comprehensive examination of all possible combinations of absorber layers we have identified a double absorber layer structure that exhibits an impressive efficiency exceeding 35%. To further enhance our understanding of the underlying factors influencing efficiency, we generated a dataset of 3490 samples. These samples were characterized by 20 input features and four attributes, including the efficiency of the perovskite structure. Leveraging machine learning approach, we developed model using the Random Forest algorithm to predict the efficiency and classify the structures into four distinct classes. Our findings contribute valuable insights into the optimized design of perovskite solar cells, offering a pathway towards achieving higher efficiencies and advancing the field of renewable energy.

Theoretical verification of using the Ga-doped ZnO as a charge transport layer in an inorganic perovskite solar cell

The study encompasses the idea to employ a single bandgap-graded transport layer in lieu of two different (transparent conducting oxide and electron transport layer) layers in the perovskite solar cell to increase the overall device functionality. Numerical simulation has been used to investigate the cell performance parameters. The thickness of the absorber layer has been altered in relation to the defect density to identify the optimal cell parameter values. Maximum power conversion efficiency (PCE) has been recorded as 22.17% at 1E13 cm−3 defect density in the absorber. These findings demonstrate the numerical modeling limitations for the relationship between defect mechanism and performance. The activation energy and effects of series resistance (R s) on solar cells have also been assessed. The temperature degradation gradient of the proposed structure GZO/CsGeI3/NiO/Au has been found to be 3% only with a PCE of 22.17%, which validates the concept of using a bandgap-graded transport layer and paves the way for a new era for perovskite research.

AB-INITIO study of electronic, mechanical, optical and thermoelectric properties of KGeCl3 for photovoltaic application

In this theoretical study, the potential of KGeCl3 was investigated as a lead-free perovskite active layer for perovskite solar cells. Calculations of the structural, electronic, elastic, optic, and thermoelectric properties of KGeCl3 in its cubic, tetragonal, and orthorhombic phases were performed using the generalized gradient approximation (GGA) within the wien2k package. The findings demonstrated that the tetragonal crystalline structure of KGeCl3 exhibited the least energy content, rendering it the most thermodynamically stable phase. It was found that the electronic band structure of KGeCl3 exhibited a direct band gap of 0.92 eV, thus positioning it as a material with promise for utilization as a photovoltaic absorber. Furthermore, the elastic properties of KGeCl3 were calculated, indicating the presence of suitable mechanical stability for practical applications. Additionally, the optical properties and thermoelectric performance of KGeCl3 were examined, thereby highlighting its potential for incorporation into thermoelectric devices. In summary, our research showcases how KGeCl3 holds significant promise as a viable substitute for lead-based perovskite materials in applications such as solar cells and other optoelectronic devices.

Design and Synthesis of Fluorinated Quantum Dots for Efficient and Stable 0D/3D Perovskite Solar Cells

AbstractDimensionality engineering involving the low‐dimensional and 3D perovskites has been demonstrated as an efficient promising strategy to modulate interfacial energy loss as well as instability in perovskite solar cells (PSCs). Herein, the use of fluorinated Cesium Lead Iodide (CsPbI3) perovskite quantum dot (PQD) is first reported as interface modification layer for PSCs. The binding between the CsPbI3 PQD surface and native oleic acid (OLA)/oleylamine (OAm) ligands is governed by a dynamic adsorption–desorption equilibrium. Perfluorooctanoic acid (PFA) with stronger binding affinity and more hydrophobic nature is explored to partially replace OLA to prepare the fluorinated ligand capped CsPbI3 PQDs (F‐CsPbI3). Through optimization of the addition of PFA during hot‐injection synthesis, the in situ treated F‐CsPbI3 PQDs display reduced surface defect states, higher photoluminescence quantum yields together with improved stability. Subsequently, both CsPbI3 and F‐CsPbI3 PQDs are utilized as interface engineering layer in PSCs, delivering the best efficiency values of 21.99% and 23.42%, respectively, which is significantly enhanced compared to the control device (20.37%). More importantly, benefiting from its more hydrophobic properties, the F‐CsPbI3 PQD treated device exhibits excellent ambient storage stability (25 °C, relative humidity: 35–45%), retaining over 80% of its initial efficiency after 1500 h aging.

Enhanced UV Absorption By 2D MoS2 Nanoparticles

MoS2 is one of the promising 2D materials that caught the interest of many research fields[1], [2] due to their size-dependent tunable bandgap and attractive magnetic, optical, and electrical properties[3]. Furthermore, recently there has been a growing interest in utilizing MoS2 for solar cell applications that demonstrated measurable device enhancements[4]–[6]. Hence, there is a great interest in understanding its potential for solar energy harvesting. In this study, we show a simple method to deposit a 2D layer of MoS2 nanoparticles (NPs) on top of Aluminum-doped Zinc oxide (AZO) layer (transparent conductive oxide) and investigate its spectral response and potential for application in optoelectronic systems.A thin film of 80 nm AZO layer was grown on a 4-inch quartz wafer using thermal Atomic Layer Deposition (ALD) with a 1:19 ratio which has shown good electrical and optical qualities for solar cell applications[7]. We deposited the MoS2 by spin-coating it on the AZO/quartz wafers for 40 sec at 1000 rpm. Incremental coating is carried on by dispersing seven layers with 500 μL of MoS2 in each step using a precise pipet to a cumulative dispersion volume of 3500 μL. The prepared samples were characterized using a UV-Vis-NIR spectrometer (Perkin Elmer Lambda) across a wide range of wavelengths (250-1200 nm) by measuring both transmittance and reflectance and calculating absorbance. Furthermore, the base AZO/quartz and quartz background signal were measured before spin-coating as reference.The obtained data shows a high absorbance effect due to MoS2 NPs at low wavelengths (<400 nm), where it peaks around 340 nm with an approximate absorbance of ~6.7%. Upon further examination, we notice that this behavior is not linear across the whole spectrum and instead is a function of (i) wavelength and (ii) MoS2 quantity which could be partially due to the quantum confinement effect of several layers of stacked 3D MoS2 nanoparticles[8]. This phenomenon could open the possibility of utilizing this material for low-wavelength filters or UV sensing applications[9]. Also, it can potentially be utilized for quantum down-conversion[10] of high-energy photons to re-emit photons at lower energies in order to enhance solar cells’ efficiencies and reduce thermal burden; however, further investigation is needed.[1] P. Zhou, C. Chen, X. Wang, B. Hu, and H. San, “2-Dimentional photoconductive MoS2 nanosheets using in surface acoustic wave resonators for ultraviolet light sensing,” Sensors and Actuators A: Physical, vol. 271, pp. 389–397, Mar. 2018, doi: 10.1016/j.sna.2017.12.007.[2] H. Dong et al., “Fluorescent MoS 2 Quantum Dots: Ultrasonic Preparation, Up-Conversion and Down-Conversion Bioimaging, and Photodynamic Therapy,” ACS Appl. Mater. Interfaces, vol. 8, no. 5, pp. 3107–3114, Feb. 2016, doi: 10.1021/acsami.5b10459.[3] K. F. Mak, C. Lee, J. Hone, J. Shan, and T. F. Heinz, “Atomically Thin MoS 2 : A New Direct-Gap Semiconductor,” Phys. Rev. Lett., vol. 105, no. 13, p. 136805, Sep. 2010, doi: 10.1103/PhysRevLett.105.136805.[4] Y. Tsuboi et al., “Enhanced photovoltaic performances of graphene/Si solar cells by insertion of a MoS 2 thin film,” Nanoscale, vol. 7, no. 34, pp. 14476–14482, 2015, doi: 10.1039/C5NR03046C.[5] N. A. Abd Malek et al., “Ultra-thin MoS2 nanosheet for electron transport layer of perovskite solar cells,” Optical Materials, vol. 104, p. 109933, Jun. 2020, doi: 10.1016/j.optmat.2020.109933.[6] Y.-J. Huang, H.-C. Chen, H.-K. Lin, and K.-H. Wei, “Doping ZnO Electron Transport Layers with MoS 2 Nanosheets Enhances the Efficiency of Polymer Solar Cells,” ACS Appl. Mater. Interfaces, vol. 10, no. 23, pp. 20196–20204, Jun. 2018, doi: 10.1021/acsami.8b06413.[7] S. Abdul Hadi, G. Dushaq, and A. Nayfeh, “Effect of atomic layer deposited Al 2 O 3 :ZnO alloys on thin-film silicon photovoltaic devices,” Journal of Applied Physics, vol. 122, no. 24, p. 245103, Dec. 2017, doi: 10.1063/1.4990871.[8] T. Li and G. Galli, “Electronic Properties of MoS 2 Nanoparticles,” J. Phys. Chem. C, vol. 111, no. 44, pp. 16192–16196, Nov. 2007, doi: 10.1021/jp075424v.[9] Z. Lou et al., “High-performance MoS_2/Si heterojunction broadband photodetectors from deep ultraviolet to near infrared,” Opt. Lett., vol. 42, no. 17, p. 3335, Sep. 2017, doi: 10.1364/OL.42.003335.[10] A. P. Sunitha, P. Praveen, M. K. Jayaraj, and K. J. Saji, “Upconversion and downconversion photoluminescence and optical limiting in colloidal MoS2 nanostructures prepared by ultrasonication,” Optical Materials, vol. 85, pp. 61–70, Nov. 2018, doi: 10.1016/j.optmat.2018.08.038.[11] Y. Wu et al., “Monolithic integration of MoS 2 -based visible detectors and GaN-based UV detectors,” Photon. Res., vol. 7, no. 10, p. 1127, Oct. 2019, doi: 10.1364/PRJ.7.001127. Figure 1

Strain Regulation and Photophysical Properties in Halide Perovskite

Perovskite solar cells (PSCs) are regarded as the most promising new generation of green energy technology due to their outstanding device performance and simple processing technology. The strain in the active layer of PSCs is primarily caused by lower interionic and intercrystal forces, leading to an increase in defect density and high recombination of carriers, which can negatively impact the performance and stability of perovskite devices. Herein, the origins of strain in perovskite film of solution processing are revealed by conducting strain tests and characterizing photophysical processes. The impacts of strain on optical and electrical properties are summarized, including its effects on molecular interaction force, band structure, defect formation energy, activation energy of ion migration, phase segregation, and phase transition. To mitigate these negative effects, the review introduces several methods for modulating strain in perovskite films, including crystallization, component tailoring, adding additives, and modifying contact layers, which are aimed at improving carrier transport and collection efficiency. It is believed that these approaches will provide scientists with new ways of thinking and system schemes for improving the performance and stability of perovskite solar cells.

Screen-Printing Technology for Scale Manufacturing of Perovskite Solar Cells.

As a key contender in the field of photovoltaics, third-generation thin-film perovskite solar cells (PSCs) have gained significant research and investment interest due to their superior power conversion efficiency (PCE) and great potential for large-scale production. For commercialization consideration, low-cost and scalable fabrication is of primary importance for PSCs, and the development of the applicable film-forming techniques that meet the above requirements plays a key role. Currently, large-area perovskite films are mainly produced by printing techniques, such as slot-die coating, inkjet printing, blade coating, and screen-printing. Among these techniques, screen printing offers a high degree of functional layer compatibility, pattern design flexibility, and large-scale ability, showing great promise. In this work, the advanced progress on applying screen-printing technology in fabricating PSCs from technique fundamentals to practical applications is presented. The fundamentals of screen-printing technique are introduced and the state-of-the-art studies on screen-printing different functional layers in PSCs and the control strategies to realize fully screen-printed PSCs are summarized. Moreover, the current challenges and opportunities faced by screen-printed perovskite devices are discussed. This work highlights the critical significance of high throughput screen-printing technology in accelerating the commercialization course of PSCs products.

Investigating the Effect of Cross-Conjugation Patterns on the Optoelectronic Properties of 7,7′Isoindigo-Based Materials

Isoindigo (IID) is widely used as a building block for the fabrication of organic semiconductor devices. Understanding the impact of cross-conjugation and linear conjugation on the optoelectronic properties of disubstituted IID is of great importance for the design of improved materials. In this study, phenyl and thienyl groups were substituted at the cross-conjugated 7,7′ position of IID to generate three novel organic semiconductor structures with a donor–acceptor architecture. The optoelectronic properties of this IID derivative were investigated and compared with those of the 6,6′ linearly conjugated IID analogs using UV–Vis spectroscopy and cyclic voltammetry. The experimental results were compared using density functional theory calculations to provide structure–property relationships based on substitution types and attachment sites for IID. The frontier orbital energy levels of the material did not vary dramatically with the position of the substituent, while the type of substituent showed a more significant influence on the HOMO’s energy level and oscillator strength. Phenyl-disubstituted 7,7′ IID (7Ph7′Ph) and thienyl-disubstituted 7,7′ IID (7Th7′Th) materials were used as electron transport layers in perovskite solar cells with a power conversion efficiency of 5.70% and 6.07%, respectively. These observations enhance our understanding of the electronic structure and optoelectronic properties of IID, guiding the design of the next generation of IID-based semiconductors.

Multifunctional and multi-site interfacial buffer layer for efficient and stable perovskite solar cells

Perovskite solar cells (PSCs) have achieved significant success in power conversion efficiency (PCE) and stability. However, interfacial recombination and film defects still hinder the improvement of PSCs efficiency. In this study, we propose a novel interfacial buffer layer material called Ethyl p-nitrobenzoate (EPN) to enhance device performance and stability. Our results demonstrate that introducing EPN improves the film's quality, reduces defect density, relieves interfacial stress, and significantly suppresses nonradiative recombination at the interface. Density functional theory (DFT) calculations confirm that EPN can effectively passivate defects in the perovskite and SnO2 films due to its multifunctionality. Finally, we achieved a high PCE of 23.16% for the target device while significantly enhancing device stability compared to the control. This work provides new insights into the development of multifunctional multi-site interfacial buffer layers for high-performance PSCs.

Solvent engineering of SnO2 electron transport layer for high-performance perovskite solar cells

Perovskite solar cells (PSCs) show great potential as industrial photovoltaic devices due to their low fabrication cost and high power conversion efficiency. Owing to high electron conductivity and good energy level matching with perovskites, SnO2 is widely used as electron transport layers (ETLs) for PSCs. However, the agglomeration of SnO2 nanoparticles makes them have poor contact with the glass substrate and it is easy to produce defects on the film surface. Herein, acetonitrile (ACN) is used to optimize the conventional solvent of commercial SnO2 colloid to solve these problems. The addition of ACN in solvent resulted in better-performing SnO2 ETLs, thus eliminating the need for long-time ultraviolet ozone (UV-ozone) treatment of the glass substrate, which undoubtedly greatly simplified the fabrication process. The subsequent vacuum treatment of SnO2 films before annealing further improves morphology of the ETLs film and performance of the overall device. Finally, the best devices after the above solvent engineering treatment achieved an efficiency of 22.28%, increased by 16% with respect to the control device fabricated by conventional method. In addition, the long-term stability of devices was also apparently improved. This solvent engineering strategy provides a simple route to prepare high-quality SnO2 ETL for high-performance PSCs.

The hydrothermal synthesis of SNO2 nanoparticles derived from tin chloride precursor for the electron transport layer of perovskite solar cells

Tin oxide (SnO2) semiconductor is recognized as a highly promising material for the electron transport layer (ETL) in perovskite solar cells (PSC) due to their wide band gap energy and high electron mobility. This material has been considered as the potential alternative material for substituting the conventional titanium dioxide (TiO2). In the form of nanostructure material, it is expected that SnO2 as the ETL in PSC device can be significantly improved owing to its high surface area leading to more intensive photon absorption. In this present study, SnO2 nanoparticles were synthesized via the hydrothermal method with temperature variations ranging from 120 °C to 160 °C for 16 hours. The as-synthesized samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), and an ultraviolet–visible (UV-Vis) spectrophotometer. The SnO2 nanoparticles were then integrated into the PSC device as the ETL, and the performance testing was conducted using a semiconductor parameter analyzer to obtain the I-V curve. On the basis of investigation results, it has been found that the temperature used during the hydrothermal process plays a crucial role in determining the crystallinity, morphology, and band gap energy of the SnO2 nanoparticles. The results of the PSC performance test indicate that SnO2 nanoparticles synthesized at a hydrothermal temperature of 150 °C demonstrated the highest power conversion efficiency (PCE) of 3.89 %. This outcome confirms the viability of SnO2 nanoparticles produced through the hydrothermal method

Applications of Metal Oxide Charge Transport Layers in Perovskite Solar Cells

Metal oxide (MO) charge transport layers (CTLs) are widely used for fabricating highly efficient and stable perovskite solar cells (PSCs) due to their superior stability, material and preparation cost, light transmission, and charge selection. However, the complex surface states, unbalanced carrier mobility, and variable energy band structure determined by MOs can lead to additional interfacial charge recombination and transport losses within the device, which limit further improvements in device performance. Extensive research has been conducted to address these challenges. In this review, an overview of current popular MO‐CTLs and their preparation methods for PSCs are provided. Interface regulation strategies, such as passivating interface defects, modulating interface energy level alignment, and improving interface contact are also discussed, which can enhance the performance of PSCs. Meanwhile, the commonly used dopants and doping strategies for optimizing the charge transport properties of CTLs are also discussed.

Applications of Carbon‐Based Materials for Improving the Performance and Stability of Perovskite Solar Cells

Organic–inorganic hybrid perovskite solar cells (PSCs) attract many researchers in the field of photovoltaic because of their high‐power conversion efficiency and low‐cost manufacturing. However, improper interfacial charge transfer, perovskite degradation, and poor stability are major concerns for their commercialization and scale‐up. Significant efforts have been made in recent years mainly by employing different strategies such as optimizing fabrication, developing novel materials, use of additives, and an interfacial layer in PSCs. Nowadays, carbon materials are widely recognized as promising candidates for alternative usage in PSCs because of their cost effectiveness, high conductivity, appropriate work function (5.0 eV), and low‐temperature sintering process. In addition, the highly hydrophobic nature of the carbon‐based materials prevents moisture penetration into the perovskite layer, resulting in enhanced stability. This review shows how effectively carbon‐based materials can improve the performance of PSCs. First, the different carbon materials such as graphene and its derivatives, fullerenes and its derivatives, carbon quantum dots, and carbon nanotubes are described. Subsequently, the role of these carbon‐based materials employed in electron‐transport layers, hole‐transport layers, and perovskite layers in PSCs is discussed. Thus, this review highlights the recent advancements made in carbon‐based PSCs and their role in improving the performance of PSCs.

Regulating molecular stacking to construct a superior interfacial contact for highly efficient and stable perovskite solar cells

The non-radiative charge carrier recombination loss at the surface and interface of the perovskite layers in perovskite solar cells (PSCs) is the main cause of their limited power conversion efficiency (PCE). Here we propose an efficient strategy to minimize the non-radiative recombination by introducing symmetric molecules with regular arrangement at the interface between the perovskite layer and hole transport layer (HTL). One end of the symmetric molecule gets in a close contact with the terminal groups of the molecules in the HTL, while the other end promotes connection with the perovskite, resulting in an enhanced interfacial electrical contact and a better valence band energy-level alignment for efficient hole extraction. In contrast, introducing similar but asymmetrical molecules forms a dimer structure and mismatched energy levels at the interface region, which is detrimental to the carrier transport. The best-performing planar PSC with the symmetric molecular modification exhibited an increase in the PCE from 21.05% to 24.02% with a substantially enhanced fill factor of 84.0%, which can be ascribed to the synergistic effects of surface defect passivation and reduction in the interfacial energy barrier. Furthermore, the corresponding unencapsulated PSC retained 80% of the original PCE after 4,000 h of aging in dry air.

A Comparison of the Performance of MAPbI3 and MASnI3 as an Inverted Perovskite Structure Using NiO as HTL Through Numerical GPVDM Simulation

Perovskite solar cells (PSCs) are solar cells that have intriguing characteristics such as environmental friendliness and the capability for high power conversion efficiency, which have attracted study from both scientific investigation and analytical standpoints. However, lead toxicity has become a significant barrier to the widespread use of PSCs. Due to the serious environmental implications of lead, an environmentally compatible perovskite is required. Tin-based perovskite has a considerable impact, showing that it is a good hole extraction material with good mobility and low effective mass. In this study, we explore the impacts of perovskite and hole transporting layer (HTL) thickness, and intensity of light limitations, in inverted PSCs based on the structure of FTO/NiO/MAPbI&lt;sub&gt;3&lt;/sub&gt; /ZnO/Ag and FTO/NiO/MASnI&lt;sub&gt;3&lt;/sub&gt; /ZnO/Ag incorporating GPVDM (General-purpose Photovoltaic Device Model) to evaluate if MASnI&lt;sub&gt;3&lt;/sub&gt; is a viable substitute to MAPbI&lt;sub&gt;3&lt;/sub&gt;. From the simulation results, the optimized parameters obtained for PCSs under 1 sun incorporating MASnI3 were 27.97%, 0.88 a.u., 0.92 V, and 34.45 mA/cm&lt;sup&gt;2&lt;/sup&gt;. Instead, the optimized parameters obtained for PCSs incorporating MAPbI&lt;sub&gt;3&lt;/sub&gt; were 24.94%, 0.88 a.u., 0.90 V, and 31.03 mA/cm&lt;sup&gt;2&lt;/sup&gt;. The thickness of the film of both PSC architectures was optimized to provide the best suitable result. The findings show that MASnI&lt;sub&gt;3&lt;/sub&gt; is employed as a promising perovskite layer in PSCs instead of MAPbI&lt;sub&gt;3&lt;/sub&gt;.

Photoactive Properties of Transport Sol-Gel Layers Based on Strontium Titanate for Perovskite Solar Cells

In this work, we have investigated the photocurrent and spectral sensitivity of the silicon/SrTiO3:xNb/perovskite structures. The sol–gel method carried out the deposition of undoped SrTiO3 layers as well as niobium-doped (SrTiO3:Nb) layers at atomic concentrations of 3 and 6% Nb. The perovskite layer, CH3NH3PbI3−xClx, has been deposited by the vacuum co-evaporation technique. The layers have been characterized by scanning electron microscopy and X-ray diffraction measurements. The volt–ampere characteristics and spectral sensitivity of the fabricated samples have been measured under illumination with selective wavelengths of 405, 450, 520, 660, 780, 808, 905, 980, and 1064 nm of laser diodes. We have shown that for different configurations of applied voltage between silicon, SrTiO3:xNb, and CH3NH3PbI3−xClx, the structures are photosensitive ones with a variation of photocurrent from microamperes to milliamperes depending on Nb concentration in SrTiO3, and the highest photocurrent and spectral sensitivity values are observed when a SrTiO3:Nb layer with 3 at.% of Nb is used. A possible application of the proposed structure with a SrTiO3:Nb layer for perovskite solar cells and photodetectors is being discussed.

Fluorinated carbon nanotubes: a low-cost hole transport layer for perovskite solar cells

Fluorinated carbon nanotubes: a low-cost hole transport layer for perovskite solar cells

Deciphering the role of (Er3+/Nd3+) co-doping effect on TiO2 as an improved electron transport layer in perovskite solar cells

Charge injection and transport at the interface of the electron transport layer (ETL) and perovskite interface are crucial for the perovskite solar cell (PSC) device performance. Titanium dioxide (TiO2) is well established as a photoanode in numerous solar energy conversion and storage. The bandgap engineering of TiO2 by Rare-Earth (RE)-doping has become a significant way to improve the optoelectronic device performance. This study demonstrates the improved performance of Rare-Earth doped TiO2 (RETO) photoanode based solar cells under the doping of Er3+, Nd3+ and following codoping of the (Er3+/Nd3+) effect. It is note that the Er, and Nd dopants are responsible for producing Ti3+ states and the oxygen vacancies near the surface, which drives the charge transportation much more effectively. With the (Er/Nd) codoping into TiO2, the band structure of TiO2 is modified better to make a quasi-Ohmic contact with the perovskites, by fermi level shifting as well changes in the conduction band minima (ECBM) energy states. This results evidence the preliminary conformation for the improvement of Jsc and Voc. Furthermore, the photoluminescence (PL) emission quenching effects of perovskite-deposited RETO attributes the suppression in the charge recombination. By insight into all these favourable results in the(Er3+/Nd3+) codoped TiO2, the RETO photoanode-based perovskite solar cell (PSC) devices were constructed and exhibited improved photovoltaic properties. The composition of (Er0.002Nd0.002Ti0.996O2) ETL employed PSC reported with a better photoconversion efficiency (PCE %) among all the compositions.

Molecule‐Assisted Chemical Bath Deposition of Tin Oxide Electron Transport Layers in Perovskite Solar Cells

Chemical bath deposition (CBD) is a widely used approach to deposit the tin oxide (SnO2) electron transport layer (ETL) in the perovskite solar cell (PSC). However, the defect states in the CBD‐resulted SnO2 ETLs limit the electron extraction/transport from the perovskite to the ETL and lead to poor PSC performance. Herein, ethylenediaminetetraacetic acid dipotassium (EDTA‐2K) is used as an additive in the CBD precursor of the SnO2 ETL, which results in the chelation of Sn2+ and EDTA during the hydrolysis process. This strategy decreases the concentration of free Sn2+ in the precursor for hydrolysis and slows down the CBD process, thus attributes to the decreased surface defect states as well as the enhanced conductivity of the ETL. As a result, the EDTA‐2K additive makes the CBD SnO2 ETL with efficient electron extraction and transporting capability. The champion device achieves a power conversion efficiency (PCE) of 21.87%, which is significantly higher than that of the pristine CBD SnO2‐based device (20.25%). In addition, the device with an active area of 1.21 cm2 achieves a high PCE of 19.23%. This strategy makes the CBD SnO2 an excellent ETL candidate for the development of low‐cost and large‐scale PSCs.