Active Layer Of Solar Cell Research Articles

A high-efficiency clay mineral based organic photocatalyst towards photodegradation of butyl xanthate in mineral processing wastewater

The organic solar cell active layer, well known for excellent visible light response capability, is regarded as a potential candidate for photocatalytic degradation of organic wastewater. However, the poor dispersibility in water due to its hydrophobicity property severely limited the degrading efficiency. In this work, a novel composite photocatalyst PM6:IDT8CN-M/CK2 with a broad visible absorption spectrum and non-toxicity was first synthesized through the intercalation compounding method. A good dispersibility of PM6:IDT8CN-M in wastewater was achieved with the help of rich interlamellar porosity and good hydrophilicity of calcined kaolin. This composite photocatalyst was successfully applied to the SBX photocatalytic degradation in mineral processing wastewater, and the SBX pollutants can be completely degraded within 10 min under the condition of visible light irradiation. Compared with other reported photocatalysts, the photocatalytic degradation efficiency of SBX was dramatically improved by at least seven times. Moreover, PM6:IDT8CN-M/CK2 has remarkable stability, sustaining degradation efficiencies of over 90 % in 60 cycles. Notably, the organic solar cell active layer in PM6:IDT8CN-M/CK2 can achieve carrier rapid separation and transport, enhancing the generation of active oxides (∙O2–, and ∙OH, etc.). At the same time, the large surface area of PM6:IDT8CN-M/CK2 provides a suitable environment for the oxidation reaction of active radicals with SBX to achieve this efficient photocatalytic degradation. Overall, this work not only extends the application scope of organic solar cell active layer, but also develops a high-efficiency SBX removal technique for the treatment of mineral processing wastewater.

Tactic of A−D−A scheme organic photocatalyst with broad spectral feature of absorption enables photocatalytic performance improvement

Breakthrough in organic pollutant photodegradation is achieved by linking the photocatalysis technology with the excellent photovoltaic nature of bulk heterojunction organic solar cell (BHJ-OSC) active layers. The first pure organic photocatalytic system built to degrade methylene blue (MB)-laden water by associating biochar supporter with active layers, fabricating a subset of organic photocatalysts, it is the first result of A−D−A scheme to date. The champion catalyst C-PM6:TPA-PDI:PIID-ClBF with excellent wide absorption spectra and fine tunable energy level exhibits greater potential in solar harvesting and prolonging charge lifetime, as well as high reusability and no insoluble residuals after treatment. As a result, this strategy both benefits the production of reactive oxygen species and eliminates concerns regarding insoluble residuals, subtly coping with the common disadvantages of most existing photocatalysts. The C-PM6:TPA-PDI:PIID-ClBF successfully degraded MB with a remarkable efficiency of 100 % achieved in 12 min, while also can maintain this high efficiency for up to 100 cycles, as long as the active materials remain active. These findings step forward in developing photocatalysts that are environmentally friendly and affordable, elucidating significant implications of advancing series of BHJ-OSCs-like photocatalysts for the removal of organic pollutants.

Light Management Investigation of Transparent DSSC based on Ln3+ ion doped BaO-ZnF2-B2O3-TeO2 Glass (Ln3+ = Dy3+/Sm37Eu3+) as UV Down-conversion Material

Solar irradiance to electrical energy conversion could be achieved via photoelectric effect using solar cells device. However, not all solar wavelengths could be captured and converted by the active layer of solar cell. The absorption limitation associated with the bandgap energy of solar cell active layer in the ultraviolet region (high photon energy) and infrared region (low photon energy) leads to 70% energy loss. Introducing a material that can convert higher photon energy to lower photon energy that is suitable with the bandgap energy of the solar cell provides a solution to this problem. In the present work, glass materials based on BaO, ZnF2, B2O3, TeO2, and Ln2O3 (Ln2O3 = Dy2O3, Sm2O3, and Eu2O3) were developed using conventional melt and quenching technique and applied as down-conversion (DC) element in dye-sensitized solar cell (DSSC). The absorption spectra of Z907 as dye photosensitizer was measured as well as the absorption spectra of DC glass. The DC glass emission spectra were also investigated to know the compatibility between the absorption of solar cell and the emission band of the DC glass. The current-voltage of the DSSC was measured while placing the DC glass on top of the solar cell device. The electrical parameters, such as power conversion efficiency, fill factor, short-circuit current, and open-circuit voltage, were then determined to analyze the effect of DC glass application on the performance of DSSC. DC glass with 1.5Eu produced an efficiency of 2.03%, showing the best result among other lanthanide ions.

Enhancing the Efficiency and Stability of Perovskite Solar Cells through Defect Passivation and Controlled Crystal Growth Using Allantoin.

In this study, we present a robust approach that concurrently manages crystal growth and defect passivation within the perovskite layer through the introduction of a small molecule additive─allantoin. The precise regulation of crystal growth in the presence of allantoin yields perovskite films characterized by enhanced morphology, larger grain size, and improved grain orientation. Notably, the carbonyl and amino groups present in allantoin passivate under-coordinated Pb2+ and I- defects, respectively, through molecular interactions. Trap density in the perovskite layer is measured, and it is 0.39 × 1016 cm-3 for the allantoin-incorporated device and 0.83 × 1016 cm-3 for the pristine device. This reduction in defects leads to reduced trap-assisted nonradiative recombination, as confirmed by the photoluminescence, transient photo voltage, and impedance measurements. As a result, when these allantoin-incorporated perovskite films are implemented as the active layer in solar cells, a noteworthy efficiency enhancement to 20.63% is attained, surpassing the 18.04% of their pristine counterparts. Furthermore, devices with allantoin exhibit remarkable operational stability, maintaining 80% of their efficiency even after 500 h of continuous illumination, whereas the pristine device degraded to 65% of its initial efficiency in 400 h. Also, allantoin-incorporated devices exhibited exceptional stability against high humidity and elevated temperatures.

Grain growth of ZnO nanocrystals synthesized in polyol medium with polyvinylpyrrolidone additives

In this work, we have investigated the influence of annealing temperature on the grain growth of zinc oxide nanocrystals synthesized in ethylene glycol and isothermally calcined at Ta: 300 °C, 500 °C, 700 °C for 60 min at the ambient atmosphere. The effect of polyvinylpyrrolidone (PVP) addition and annealing temperature on ZnO nanocrystal's phase composition, structural (scattering domain size of nanocrystallites L, unit lattice parameters a, c, and unit volume Vunit, theoretical density ρx) parameters, morphological (size, shape, specific surface area SSA) features, chemical composition, and grain growth kinetics were determined. It was found that Ta caused the increase in L of single-phase ZnO nanocrystals from 18 nm to 40 nm (with adding PVP) and to 45 nm (without adding PVP). Despite the surfactant composition, submicron grain sizes (D = 120–150 nm) were observed at Ta = 700 °C. The activation energy of grain growth was Q = 121.4 kJ/mol (without adding PVP) and Q = 126.4 kJ/mol (with adding PVP), while grain growth exponent was n = 1.9 (without adding PVP) and n = 2.0 (with adding PVP). ZnO nanocrystals annealed at 700 °C are forthcoming in the design of the active layers of solar cells, and at (300–500) °C are suitable for thermoelectric converters.

Synthesis and characterization of lithium-doped copper zinc tin sulfide (CZTS) thin films

The non-toxic nature and remarkable optoelectronic properties of kesterite (Cu2ZnSnS4 and CZTS) make CZTS a potential candidate for solar cell absorber layer material. Since alkali metal doping has shown a performance boost of active layers of solar cells, this work investigates the effects of significant lithium doping on sol-gel-produced CZTS thin films. CZTS- and lithium (Li)-doped CZTS thin films were prepared using the spin coating technique. The variation of structural, morphological, and optical properties of CZTS due to Li-doping has been studied by x-ray diffraction, scanning electron microscopy, and UV–visible spectroscopy techniques. All the synthesized LixCu2−xZnSnS4 (x = 0, 0.2, 0.4, 0.6) films showed fine crystallinity with average crystallite sizes of 4.745, 6.013, 6.255, and 6.404 nm, respectively. The average grain size decreases from 0.336 to 0.310 µm via increasing Li concentration. The inclusion of Li increased the bandgap energy ranges from 1.5 to 1.808 eV. The Li0.6Cu1.4ZnSnS4 thin showed the highest absorption coefficient of 3.505 × 104 cm−1 among all the prepared thin films. A high optical conductivity over 1014 s−1 was observed for CZTS, which further increased with an increased Li concentration. The synthesized structures showed enhanced characteristics suitable for solar cell application.

Optical and structural characterization of CsPb(I1-xBrx)3 nanomaterials prepared by the mechanochemical method

Hybrid organic-inorganic lead halide perovskites (LHP) are gaining considerable attention due to their wide range of potential applications, particularly as an active layer in solar cells and light-emitting devices owing to their excellent light-harvesting and photoluminescence emission properties. Considering their high color purity and color-tunability, high photoluminescence quantum yield (PLQY), easy fabrication, and cost-efficiency, LHP are promising candidates to compete with the traditional active layer in solid-state lighting. The PL emission of CsPbX3 (X = I, Br, Cl) covers the entire visible range from 400 to 730 nm and can be easily tuned via halide replacement in the I ↔ Br ↔ Cl series. In this work, photoluminescence (PL), luminescence excitation, UV/VIS/NIR absorption, structural and morphological properties of CsPb(I1-xBrx)3 (x = 0–1) nanosized powders prepared by the mechanochemical synthesis method is investigated at 80K and room temperature. A narrow PL peak with full width at half maximum (FWHM) = 16.5 and 6.6 nm was observed at room temperature and 80K from CsPbBr3, respectively. The relation between structure and optical properties of nanopowders is discussed. It is shown that the halide exchange mechanism is an effective approach for fabrication of defect-free materials.

Light absorption enhancement in organic solar cell using non-concentric Ag:SiO2 core-shell nanoparticles

Low solar energy conversion efficiency prevents the widespread of organic solar cells; hence, metal nanoparticles have been used to overcome this problem without increasing cell thickness. We investigated light absorption enhancement in view of the embedment of Ag:SiO2 core-shell nanoparticles of different shell thicknesses, core offsets, offset orientation angles, and vertical mismatches between neighboring particles. The simulations were carried out using the finite element method. This is the first investigation in the use of asymmetric nanoparticles. At optimized conditions, absorption enhancement up to 345% compared to the one without the nanoparticles could be achieved. The enhancement was found much higher than that of the published values. The enhancement results were mainly from the increase of near-field localization and scattering in the active layer of solar cells due to the excitation of Fano resonances. The resonance occurred due to the non-symmetric nature of the core-shell nanoparticles.

Enhanced surface morphology and photovoltaic properties of a new class of material copper silver bismuth iodide solar cell

Newly discovered copper silver bismuth iodide films have attracted a lot of interest as a lead-free emerging material for active layers of solar cells because of their promising optical and photovoltaic properties. This study is the first to describe the optimization of the annealing temperature of Cu6AgBiI10 solar cells. By using a single-step spin coating technique, the films were fabricated, in which hot casting drops were cast onto the preheated substrates. The trigonal crystal's structure was confirmed using X-Ray Diffraction and surface morphology was observed through scanning electron microscopes of synthesized films. The mapping of energy dispersive X-ray spectrometers confirms that the elements in the films are evenly distributed. In this work, we examine the optical and photovoltaic characteristics of the ITO/SnO2/Cu6AgBiI10/P3HT/C/Ag structure for the first time. Our optical investigation revealed high absorbance and low reflectivity CABI film at 150 °C. According to analysis of photovoltaic attributes, we were able to achieve maximum current density of 0.45 mA/cm2 and power conversion efficiency of 0.041%. These results should be helpful in the development of environmentally-friendly Cu–Ag–Bi–I base solar cells, as well as a variety of other devices such photo detectors or LED's.

Metal oxide nanoparticles as an electron-transport layer in perovskite solar cell

The research on the application of lead-free perovskite materials as an active layer in solar cells has been positively carried out for the last few years. Although the efficiency of lead-contained metal halide-based Perovskite has reached above 25%, but lead is a highly toxic substance that is hazardous to the environment, and this is one of the obstacles to their commercialization. In this article, a Sn-based Perovskite (CH3NH3SnI3) solar cell with two distinct electron transport layers was simulated using GPVDM (General Purpose Photovoltaic Device Model) and fabricated with a simple sol-gel method. Along with the absorber layer, the charge transport materials also play an essential role in extracting electrical power. The comparison of ZnO and TiO2 as electron collectors has been investigated and characterized, the hole-carrying layer has been eliminated for better findings. Remarkably, we achieve an efficiency of 7.33% and 6.75% in simulation and 6.90% and 5.81% from fabricated devices using ZnO and TiO2, respectively.

Cellulose acetate-derived ternary-doped hierarchically porous carbons blended perovskite active layers for solar cells and X-ray detectors

Herein, we have synthesized hetero-atoms (nitrogen (N), sulfur (S), phosphorus (P))-doped porous carbons (PCs) which upon dispersion in perovskite precursor solution with different (2–8 wt.%) modify its morphology and improve optoelectronic characteristics of the perovskite active layer (AL) results into enhancing efficiency and stability of perovskite solar cells (PSCs). The results indicate that PCs (6 wt.%) modifies perovskite AL-constructed PSCs and X-ray photodetectors outperform other investigated devices. The excellent PSCs (AL@NSPCPC) demonstrate power conversion efficiency (PCE) of 13.81%, fill factor (FF) 64.77%, current density Jsc (23.518 mA/cm2), and open circuit voltage Voc (0.906 V), which is significantly higher than pristine AL 10.42%, 57.01%, 20.423 mA/cm2, and 0.895 V, respectively. Furthermore, the sample (AL@NSP-CPC) when constructs in the geometry of an X-ray photodetector, shows 15.56 μA/cm2, 4.66 mA/Gy·cm2, 5.26×10−4 cm2/V·s, and 3.58 × 1015 cm−3 of collected charge density (CCD), dark current density (DCD), sensitivity, mobility, and trap density, respectively. Thus, heteroatom-doped PCs modified perovskite layers demonstrate promise for constructing PSCs and X-ray photodetectors opening future research in exploiting these abundant, and inexpensive carbons materials having large mobility and tunable morphology along with surface passivation at perovskite/hole transport layer (HTL) interface to further enhance their photovoltaic parameters.

Anthracene-bridged sensitizers for environmentally compatible dye-sensitized solar cells: In silico modelling and prediction

Advancement in solar cells has gained the attention of researchers due to increasing demand and renewable energy sources. Modeling of electron absorbers and donors has been performed extensively for the development of efficient solar cells. In this regard, efforts are being made for designing effective units for the active layer of solar cells. In this study, CXC22 was utilized as a reference in which acetylenic anthracene acted as a π bridge and infrastructure was D-π-A. We theoretically designed four novel dye-sensitized solar cells JU1-JU4 by utilizing reference molecules to improve the photovoltaic and optoelectronic properties. All designed molecules differ from R by donor moiety modifications. Different approaches were done to R and all molecules to explore different analyses like binding energies, excitation energies, dipole moment, TDM (transition density matrix), PDOS (partial density of states), absorption maxima, and charge transfer analysis. For the evaluation of results, we used the DFT technique and the findings demonstrated that the JU3 molecule showed a better redshift absorption value (761 nm) as compared to all other molecules due to the presence of anthracene in the donor moiety which lengthens the conjugation. JU3 was proven to be the best candidate among all due to improved excitation energy (1.69), low energy band gap (1.93), higher λmax value, and improved electron and hole energy values leading toward higher power conversion efficiency. All the other theoretically formed molecules exhibited comparable outcomes as compared to a reference. As a result, this work revealed the potential of organic dyes with anthracene bridges for indoor optoelectronic applications. These unique systems are effective contributors to the development of high-performance solar cells. Thus, we provided efficient systems to the experimentalists for the future development of solar cells.

The nature of excitons in PPDT2FBT:PCBM solar cells: Role played by PCBM

In organic semiconductor-based bulk heterojunction solar cells, the presence of an acceptor increases the formation of charge-transfer (CT) excitons, thereby leading to higher exciton dissociation probabilities. In this work we used steady-state electroabsorption (EA) measurements to probe the change in the nature of excitons as the blend composition of the solar cell active layer material was varied. We investigated blends of poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c]-[1,2,5]thiadiazole)] (PPDT2FBT) and (6,6)-phenyl C71 butyric acid methyl ester (PCBM). Analysis of the EA spectra showed that in the presence of a fullerene-based acceptor, like PCBM, CT characteristics of the excitons were modified, though no new CT signature was observed in the blend. Enhancement in the CT characteristics in the blend was reflected in photoluminescence (PL) measurements of the blends, where PL quenching of ∼63% was observed for 1% PCBM. The quenching reaches saturation at about 20% PCBM. However, efficiency of the device increased with a PCBM percentage beyond 20%. Maximum efficiency was obtained for the blend with 50% PCBM, among the blend compositions studied in this work, indicating the optimum concentration of PCBM for best power conversion efficiency to be around that value. When we compared the experimental results with simulations, the variation of the device efficiency with PCBM percentage was shown to arise from multiple factors, such as an increase in the polarizability and dipole moment of excitons, and the efficiency of the carrier collection from the bulk of the active layer.

Theoretical study of carbon nanotubes as candidates for active layer in solar cells

We present results of theoretical calculations of electronic and optical properties for 35 finite Carbon NanoTubes (CNTs). The quantities calculated are: HOMO and LUMO energies, energy gaps, and, most important, visible and infrared spectra. Calculations were performed in DFT and TDDFT formalism. The motivation of this study was examination of possibility of application of CNTs as an active layer in organic solar cells (OSCs). We propose to use CNTs as an active layer for their exceptional property, namely, large exciton diffusion length. This opportunity would allow to construct an OSC in a layer architecture, where thickness of the layer could be sufficient for an absorption of significant part of light and, at the same time, large exciton diffusion length would preserve effectiveness of excitons dissociation into charges. An important aspect is that CNTs should be parallelly ordered in order to maximize the advantage of large exciton length. This way, we hope to radically improve the OSC efficiency and to overcome Bulk HeteroJunction (BHJ) architecture limitations, where – besides last achievements – the efficiency is still substantially lower than theoretical predictions. Our calculations show that overall absorption of CNTs is large in visible and infrared regions. This opportunity imply that necessary condition for construction of layer high-efficient CNT-based OSCs is fulfilled.

Portable integrated photo-charging storage device operating at 3 V

The integration of an energy harvesting device and an energy storage device into one unit has been widely studied as a distributed power source. Herein, we propose a high-voltage-driven photo-charging storage device, integrating a series-connected perovskite solar cell and an ionogel-based solid supercapacitor. The photo-charging storage device exhibits high overall efficiencies of 13.17 % and 9.87 % at 1 mA cm−2 and 20 mA cm−2, respectively, attributed to its high storage efficiency of over ∼ 70 % at all discharge current densities. This high discharge current density of 20 mA cm−2 is the record value for all reported integrated solar cells and electric double-layer capacitor systems. Moreover, the photo-charging storage device maintains 78.6 % of its overall efficiency after 100 cycles under AM 1.5 G illumination and exhibits remarkable cycle performance under indoor light illumination. To understand the interfacial behavior of the photo-charging storage device, impedance spectroscopy is performed for the first time. In addition, to avoid the decomposition of the perovskite solar cell active layer with moisture, an encapsulation process is conducted, which enables the device to remain operational at 3 V after 8 weeks. These results underline the high potential of this photo-charging storage device as a portable power source.

Effects of Different Anti-Solvents and Annealing Temperatures on Perovskite Thin Films

Since perovskite materials are currently mostly used in the active layer of solar cells, how to maximize the conversion efficiency of the active layer is the most urgent problem at present. In this regard, the extremely low voltage loss and tunable energy gap of methyl lead iodide (MAPbI3) perovskites make them very suitable for all perovskite solar cell applications, and are also compatible with silicon crystalline systems. Therefore, the future development of MAPbI3 perovskite will be very important. The key point of film formation in MAPbI3 is the addition of anti-solvent, which will affect the overall quality of the film. Whether it can be used as an excellent active layer to improve the application value will be very important. Therefore, the research purpose of this topic “Effects of different anti-solvents and annealing temperatures on perovskites” is to complete the basic research and development of a light-absorbing layer of a solar cell element, in which three different anti-solvents need to be matched with each other as the active light-absorbing layer of a solar cell. Through optimization, using the chemical properties of different anti-solvents and different annealing temperatures, combined with the low-process-cost characteristics of organic materials and many other advantages, we researched the optimized process methods and parameters to improve the absorption efficiency of the active light-absorbing layer.

Rational selection of the polymeric structure for interface engineering of perovskite solar cells

<h2>Summary</h2> Tedious trial-and-error procedures are commonly practiced for surface modification of the perovskite solar cell (PSC) active layers. A guideline to rationally choose the passivating functional groups of the polymeric structure that is eminently effective in passivating the charged defects and elongating the device lifetime is hence in urgent demand. Herein, three prototypical polymers, poly(vinyl acetate) (PVA), polyethylene glycol (PEG), and poly(9-vinylcarbazole) (PVK), are selected to investigate the structural effect of the polymeric modification agents on the PSCs. We found that PVA possesses the Lewis base functional group with the minimized steric hindrance and the strongest electron-donating ability, enabling the most effective defect passivation on the perovskite film surface and the most enhanced carrier diffusion capacity. It demonstrates a power conversion efficiency (PCE) of 23.20% and noticeably enhanced operational stability. Our work provides important insights toward the selection of polymeric modification agents for high-performance and long-term stable PSCs.

First-Principle Study of CsPbBr3 and CsPbI3 Perovskite Solar Cells

Due to the outstanding power conversion efficiency (PCE), lightweight, flexible, and low manufacturing cost, perovskite solar cells (PSCs) attract a lot of attention as the most promising candidate for the next generation of solar cells. However, the issue of poor intrinsic stability of the absorber materials and operational stability of devices remains unsolved. In this study, first-principle calculations were performed on the CsPbX3 (X = Br or I) perovskites to provide insight into the structural, mechanical, vibrational and electronic properties of CsPbBr3 and CsPbI3 for their applications as active layers of solar cells. It was found that the calculated lattice parameters are in good agreement with the experimental results. CsPbBr3 and CsPbI3 have negative energy of formation, which implies that the materials are thermodynamically stable. The calculated band structures indicate that CsPbBr3 and CsPbI3 are semiconductors with direct bandgaps along R-symmetry point. Furthermore, cluster expansion and simulations of Monte-Carlo were performed to identify new possible CsPbBr1-xIx structures and evaluate the effect of temperature on the system. The ground-state search generated 26 new multi-component CsPbBr1-xIx structures, and the temperature-profile showed that the system mixes well at ∼800 K. Thus, the phase stability insight is crucial for the development of these promising perovskite solar cells.

Theoretical Study of Carbon Nanotubes as Candidates for Active Layer in Solar Cells

Theoretical Study of Carbon Nanotubes as Candidates for Active Layer in Solar Cells

Mixed molecular orientations promote charge transport in bulk heterojunction solar cells.

By systematically varying the molecular orientation of poly(3-hexylthiophene-2,5-diyl) (P3HT) in P3HT:fullerene bulk heterojunctions, we show that a mixed face-on and edge-on texture can be beneficial for out-of-plane charge flow in solution processed organic bulk heterojunction solar cells. These results implicate the need to balance in-plane and out-of-plane pathways for efficient charge percolation in bulk heterojunctions.