Film Solar Cells Research Articles

Modulating Ion Deposition and Crystallization of Sputtered Perovskite Films for Efficient and Stable Solar Cells

Modulating Ion Deposition and Crystallization of Sputtered Perovskite Films for Efficient and Stable Solar Cells

Optimization of LPCVD Deposition Conditions of Silicon-Rich Silicon Nitride to Obtain Suitable Optical Properties for Photoluminescent Coating

Silicon nitride is a commonly used material for ceramic applications and in the fabrication processes of integrated circuits (ICs). It has also increased in interest from the scientific community for use as a functional coating due to its physical, mechanical, electrical, and optoelectronic properties. In particular, silicon-rich silicon nitride (SRSN) has been considered in the photovoltaic industry as a down-conversion film for solar cells. In this work, SRSN films have been obtained by the Low-Pressure Chemical Vapor Deposition (LPCVD) technique at low to moderate deposition temperatures with a variation in the precursor gas pressure ratio. The SRSN films showed a wide photoluminescence (PL) in the visible region (without a high-deposition temperature or annealing process) and suitable optical properties (refractive index and absorption in the UV) to be used as photoluminescent coating on silicon solar cells. The absence of high-deposition temperatures could preserve the original structure of silicon solar cells, once the SRSN layer was applied. In addition, control of the reactive gas pressure ratio and deposition temperature showed an influence on the refractive index, the surface roughness, and the PL emission.

Fabrication of Anti-reflective Film for Solar Cells through Hot Embossing Process using Laser Patterned Mold: Parametric Analysis and Optimization

Fabrication of Anti-reflective Film for Solar Cells through Hot Embossing Process using Laser Patterned Mold: Parametric Analysis and Optimization

Solvent‐Engineering‐Assisted Ligand Exchange Strategy for High‐Efficiency AgBiS2 Quantum Dot Solar Cells

AbstractAs the initial synthesized colloidal quantum dots (CQDs) are generally capped with insulating ligands, ligand exchange strategies are essential in the fabrication of CQD films for solar cells, which can regulate the surface chemical states of CQDs to make them more suitable for thin‐film optoelectronic devices. However, uncontrollable surface adsorption of water molecules during the ligand exchange process introduces new defect sites, thereby impairing the resultant device performance, which attracts more efforts devoted to it but remains a puzzle. Here, we develop a solvent‐engineering‐assisted ligand exchange strategy to revamp the surface adsorption, improve the exchange efficiency, and modulate the surface chemistry for the environmentally friendly lead‐free silver bismuth disulfide (AgBiS2) CQDs. The optimized AgBiS2 CQD solar cells deliver an outstanding champion power conversion efficiency (PCE) of up to 8.95 % and improved long‐term stability. Our strategy is less environment‐dependent and can produce solar cells with negligible performance variance for several batches across several months. Our work demonstrates the critical role of solvents for ligand exchange in the surface chemistry of CQDs and the realization of high‐performance photovoltaic devices in a highly reproducible manner.

CBD-synthesized Mg-doped CdS thin films for hybrid solar cells and self-powered photodetectors

Mg-doped CdS samples were deposited via chemical bath deposition onto fluorine-doped tin oxide slides with varying levels of Mg-doping. Structural analysis revealed improved crystal quality in CdS films upon Mg incorporation. Morphological examinations indicated a reduction in grain size alongside appearance of smooth, void-free surfaces particularly evident at 3 % Mg-doping. Mg-doping also resulted in enhanced transparency of CdS films, notably at 3 % and 5 % within the visible spectrum. Efficient exciton dissociation was observed in hybrid solar cells based on 1 % and 3 % Mg-doped CdS, as evidenced by photoluminescence. Top-performing solar cell achieved an efficiency of 0.220 %, nearly seven times that of control device. 5 % Mg-doped CdS-based photodetectors exhibited favorable photosensing characteristics: a responsivity of 0.011 A/W, detectivity of 4.4 × 108 Jones, external quantum efficiency of 3.1 %, and rise/decay times of 26/25 ms at zero bias. These findings underscore beneficial effects of Mg-doping on both hybrid solar cell and self-driven photodetector performance.

Synergistic Passivation of Buried Interface and Grain Boundary of Tin–Lead Mixed Perovskite Films for Efficient Solar Cells

Synergistic Passivation of Buried Interface and Grain Boundary of Tin–Lead Mixed Perovskite Films for Efficient Solar Cells

Regulation of the Buried Interface to Achieve Efficient HTL-Free All-Inorganic CsPbI2Br-Based Perovskite Solar Cells.

The large voltage loss (Vloss) mainly stems from the mismatch between the perovskite film and electron transport layer in CsPbI2Br-based all-inorganic perovskite solar cells (I-PSCs), which restricts the power conversion efficiency (PCE) of devices. To address this issue, potassium benzoate (BAP) is first introduced as a bifunctional passivation material to regulate the TiO2/CsPbI2Br interface, reduce the Vloss, and improve the photovoltaic performance of CsPbI2Br-based I-PSCs. Eventually, the champion PCE of CsPbI2Br-based I-PSCs without a hole transport layer modified by BAP (Target-PSCs) improves to 14.90% from the 12.14% of reference PSCs. The open-circuit voltage (Voc) increases to 1.27 V from the initial 1.14 V after BAP modification. A series of characterizations show that BAP modification can not only optimize the energy level alignment of I-PSCs but also passivize the surface defects caused by uncoordinated Cs+/Pb2+. Moreover, the Target-PSCs without encapsulation demonstrate better thermal stability, which can maintain 107.6% of the original PCE after annealing at 160 °C for 140 min in humid air. While the reference PSCs only maintain 76.5% of their initial PCE after annealing at the same process. This work provides a simple strategy to modify the buried interface and improve the performance of CsPbI2Br-based I-PSCs.

Aromatic carboxyl acid regulated nanoparticle deposition and passivation of tin oxide for high performance perovskite solar cells

The composition and nano particle agglomeration of hydrolyzed species in chemical bath deposition (CBD) plays a key role in obtaining efficient SnO2 film for high performance perovskite solar cells (PSCs). In this work, the aromatic acids with varied carboxyl groups were investigated to regulate the nano particle deposition and passivate the buried SnO2/perovskite interface. The quasi in-situ dynamic light scattering and Zeta potential results indicated that the nano particle agglomeration with trimesic acid (TMA) was significantly refined throughout the whole deposition process. The TMA-SnO2 achieved an ideal energy band alignment with perovskite and released the internal residual strain, promoting the growth and crystallization of the perovskite film due to the corrdination of carboxyl groups. As a result, the interface defects were effectively passivated with enhanced efficiency and stability. The small area device based on TMA-SnO2 obtained an efficiency of 25.07 %. The devices with an enlarged area of 1.4 cm2 and the 5x5 cm2 mini-module (active area 10.054 cm2) showed impressive PCEs of 23.93 % and 22.40 %, respectively. Furthermore, the unencapsulated devices exhibit enhanced long-term stability, maintaining 80 % and 90 % of the initial efficiencies under 80 ± 5°C thermal annealing in nitrogen for 1176 h and in air condition for 3224 h, respectively.

Influence of Wrinkle Structure on Properties of Na-doped ZnO Films

Un-doped ZnO and Na-doped ZnO (NZO) thin films with various Na doping concentrations were successfully fabricated on glass substrates by a sol-gel process. The effect of Na ions at concentrations of 0, 1, 2, 3, 4, and 5% on the crystalline structure, surface morphology, and optoelectronic properties of ZnO films was studied using appropriate measurement techniques. XRD analysis revealed a polycrystalline hexagonal wurtzite structure in the NZO films. The NZO films' average crystal size ranged from 17.7 nm to 19.6 nm. SEM micrographs showed that wrinkle network appeared in the pure and doped ZnO films due to solvent evaporation during the thermal annealing process. UV-Vis spectroscopy pointed out that the average transmittance of NZO films is as large as ca. 78%. The optical bandgap of the films varied slightly between 3.235 eV for the pure ZnO and 3.246 eV for the Na 5% doped NZO film. When Na ions were doped into the NZO films, the electrical conductivity improved. Moreover, the absorption figure of merit exhibited the largest value of 0.981 Ω-1cm-1 for the fabricated NZO films, which enables the use of these films for solar cells and for other optoelectronic applications.

Effect of 4-MeV Electron Irradiation on Radiative Recombination of Cu(In,Ga)(S,Se)2 Thin Films in Solar Cells

Effect of 4-MeV Electron Irradiation on Radiative Recombination of Cu(In,Ga)(S,Se)2 Thin Films in Solar Cells

Heterogeneous Nucleation Regulation Amends Unfavorable Crystallization Orientation and Defect Features of Antimony Selenosulfide Film for High-Efficient Planar Solar Cells.

Antimony selenosulfide (Sb2(S,Se)3) has obtained widespread concern for photovoltaic applications as a light absorber due to superior photoelectric features. Accordingly, various deposition technologies have been developed in recent years, especially hydrothermal deposition method, which has achieved a great success. However, device performances are limited with severe carrier recombination, relating to the quality of absorber and interfaces. Herein, bulk and interface defects are simultaneously suppressed by regulating heterogeneous nucleation kinetics with barium dibromide (BaBr2) introduction. In details, the Br adsorbs and dopes on the polar planes of cadmium sulfide (CdS) buffer layer, promoting the exposure of nonpolar planes of CdS, which facilitates the favorable growth of [hk1]-Sb2(S,Se)3 films possessing superior crystallinity and small interface defects. Additionally, the Se/S ratio is increased due to the replacement of S/Se by Br, causing a downshift of the Fermi levels with a benign band alignment and a shallow-level defect. Moreover, Ba2+ is located at grain boundaries by coordination with S and Se ions, passivating grain boundary defects. Consequently, the efficiency is increased from 7.70% to 10.12%. This work opens an avenue towards regulating the heterogeneous nucleation kinetics of Sb2(S,Se)3 film deposited via hydrothermal deposition approach to optimize its crystalline orientation and defect features.

Preparation and performance study of organic small molecule photovoltaic donor materials in solar cells

Abstract In this study, PDPAT-BDT-BT was used as a donor material, combined with PC61BM and PC71BM as acceptor materials, to prepare a hybrid thin film for organic solar cells. In photovoltaic performance tests, this film shows advantages and good characteristics. The experimental results show that the PDPAT-BDT-BT polymer shows good performance in terms of thermal stability, optical properties, and electrochemical properties. It also shows better photovoltaic performance in the hybrid system with PC71BM, which lays a good foundation for its potential application in organic solar cells.

Gold nanorods as performance enhancers in planar perovskite solar cells: A numerical study

The quest for efficient and sustainable energy sources calls for an optimized optical design in photovoltaic technologies, particularly in perovskite solar cells (PSCs). This study focuses on the numerical analysis of integrating plasmonic non-spherical gold nanorods into realistic n-i-p MAPbI3 PSCs. The research addresses the light-harvesting enhancement, especially in near-infrared (NIR), a known limitation of metal halide PSCs. Nanorods were the selected nanostructures, as their longitudinal plasmon resonance has the potential to cover the NIR spectral limitation. The study aims to optimize the size, aspect ratio, orientation, and distance between nanorods, as well as provide insights into practical solutions for the positioning and encapsulation of the nanorods. The findings reveal that the aspect ratio and orientation of the nanorods significantly impact the absorption enhancement. Optimal outcomes are achieved with the vertical orientation of the nanorods, parallel to the stacking direction of the solar cell films. The most promising results from this study demonstrate that the incorporation of gold nanorods with small aspect ratios close to 1.5 leads to the potential enhancement of the perovskite photocurrent by at least 5 % (for spherical nanoparticles the maximum is 4.4 %). Additionally, it is also possible to reduce the layer thickness and the associated lead amount by at least 33 %, while maintaining the solar cell performance.

Solvent-Engineering-Assisted Ligand Exchange Strategy for High-Efficiency AgBiS2 Quantum Dot Solar Cells.

As the initial synthesized colloidal quantum dots (CQDs) are generally capped with insulating ligands, ligand exchange strategies are essential in the fabrication of CQD films for solar cells, which can regulate the surface chemical states of CQDs to make them more suitable for thin-film optoelectronic devices. However, uncontrollable surface adsorption of water molecules during the ligand exchange process introduces new defect sites, thereby impairing the resultant device performance, which attracts more efforts devoted to it but remains a puzzle. Here, we develop a solvent-engineering-assisted ligand exchange strategy to revamp the surface adsorption, improve the exchange efficiency, and modulate the surface chemistry for the environmentally friendly lead-free silver bismuth disulfide (AgBiS2) CQDs. The optimized AgBiS2 CQD solar cells deliver an outstanding champion power conversion efficiency (PCE) of up to 8.95% and improved long-term stability. Our strategy is less environment-dependent and can produce solar cells with negligible performance variance for several batches across several months. Our work demonstrates the critical role of solvents for ligand exchange in the surface chemistry of CQDs and the realization of high-performance photovoltaic devices in a highly reproducible manner.

16.48% Efficient solution-processed CIGS solar cells with crystal growth and defects engineering enabled by Ag doping strategy

Solution-processed Cu(In,Ga)Se2 (CIGS) solar cells suffer from serious carrier recombination and power conversion efficiency (PCE) loss because of the poor film properties and easy formation of defects. Herein, we propose Ag&Se co-selenization strategy to enhance the crystallization and passivate harmful defects of the CIGS films. The formation of Ag-Se phase during the selenization process enables the formation of large grains and suppresses the deep level defects. It is found that Ag doping can enlarge the depletion region width, lower the Urbach energy and prolong the carrier lifetime. As a result, a champion solution-processed CIGS solar cell presents a high efficiency of 16.48% with the highly improved open-circuit voltage (VOC) of 662 mV and fill factor (FF) of 75.8%. This work provides an efficient strategy to prepare high quality solution-processed CIGS films for high-performance CIGS solar cells.

Improving Hybrid Tin Halide Films of Lead-Free Perovskite Solar Cells with a Volatile Additive of Dipropyl Sulfide.

Lead-free perovskite solar cells with hybrid tin halides (Sn-PVKs) as harvesters have attracted attention with respect to eliminating the contamination of conventional hybrid lead halides. However, Sn-PVK films usually have inferior performance due to rapid crystallization and uncontrollable morphology. Moreover, Sn2+ ions suffer from irreversible oxidation that results in self-doping and device instability. Additive engineering is a key strategy for improving the quality of Sn-PVK films, but solid residues of additives could degrade the transport-recombination process. In this work, dipropyl sulfide (DPS) was introduced as a volatile additive into the precursor solution, and no residue exists in the Sn-PVK films after thermal annealing. The coordinating ability of DPS molecules stabilized Sn2+ ions to form the intermediate complex, which retards the crystallization and oxidation of Sn-PVK films. Consequently, the power conversion efficiencies of devices increase from 11.0% to 12.9% with less recombination and a lower leakage current, and the stability of the devices is improved simultaneously.

Regulation interfacial energy by reducing the Young’s modulus of perovskite film in carbon-based HTM free MAPbI3 perovskite solar cell

In ambient air, a long-chain dodecafluorosuberic acid (DFSA) with lower Young’s modulus was introduced to improve the mechanical compatibility of perovskite/carbon interface. Firstly, the carbonyl groups CO and F– in DFSA can passivate the intrinsic defects of perovskite, the DFSA effectively reduces the Young’s modulus of the perovskite and mitigates residual stress generated during perovskite annealing procedure. Most importantly, DFSA significantly enhances the Young’s modulus compatible degree between DFSA-CH3NH3PbI3 (DFSA-MAPbI3, 35.8 GPa) and carbon (6.3 GPa), alleviating the interfacial stress concentration. Based on quantitatively analysis, interfical crack driving energy (Gd) is reduced from 0.63 to 0.43 J m−2, while the adhesive fracture energy (Ga) is increased from 0.47 to 0.54 J m−2, which reduces the probability of crack propagation and ductile delamination, and is conducive to the extraction and transmission of photogenerated carrior. This was also verified in finite element simulations. Finally, the photoelectric conversion efficiency (PCE) of the organic-inorganic hybrid perovskite (MAPbI3) PSC device is improved from 10.27 % to optimal 14.12 %. After service at room temperature with relative humidity (RH) of 50–55 % and high temperature of 85 °C for 720 h, the original efficiency is maintained at 72 % and 89 %, respectively.

SnO2/Silver Nanowire/Polyimide Flexible Transparent Conductive Films for Double-Sided Perovskite Solar Cells and Heaters

SnO₂/Silver Nanowire/Polyimide Flexible Transparent Conductive Films for Double-Sided Perovskite Solar Cells and Heaters

Ionic liquid regulating perovskite film for air-processed perovskite solar cells

Air-processed perovskite solar cells (PSCs) expediate its commercialization. However, since the intrinsic moisture sensitivity disturb perovskite crystallization and morphology, the photovoltaic performance and shelf stability attenuation are inevitably occurred. Herein, 1-ethy-3-methylimidazolium tetrafluoroborate ([AOEMIM][BF4]) ionic liquids (ILs) was incorporated into perovskite interior to weaken the deleterious influence of ambient moisture on perovskite crystallization. The carboxyl and imidazole from the [AOEMIM]+ moiety passivate undercoordinated Pb2+ defects through coordination bond, while hydrophobic [BF4]- incorporating into the precursor solution protects the films from moisture destruction. Consequently, the targeted PSCs fabricated in open air achieved an impressive PCE of 19.86 % with favorable shelf stability, maintaining 93 % and 89 % of their original efficiencies after 720 h under relative humidity of 80 ± 2 % and after 240 h thermal ageing measurement at 85 °C, respectively.

Humidity Effects on Cs0.17FA0.83Pb(I0.83Br0.17)3 Thin Films for Carbon-based Perovskite Solar Cells

Org anic-inorganic hybrid perovskites have captivated the attention of researchers worldwide due to their remarkable potential for low-cost, high-efficiency solar cells. However, the reliance on controlled environments, such as dry boxes, poses a significant barrier for smaller laboratories wishing to participate in perovskite research. In this study, we investigate the influence of ambient humidity of Cs0.17FA0.83Pb(I0.83Br0.17)3 during the film formation process. Our experiments involved the fabrication of perovskite films using spin-coating techniques under different controlled humidity conditions with identical precursor preparation. The results revealed a significant decrease in film thickness under higher humidity, accompanied by a noticeable alteration in perovskite grain morphology, suggesting a complex interplay between humidity and grain formation. Furthermore, the photovoltaic performance of device with perovskite film formed in different humidity was measured. Surprisingly, despite the challenges posed by high humidity during fabrication, the solar cell efficiency only moderately decreased from 13.17% to 9.55% in average, indicating a remarkable potential of the Cs0.17FA0.83Pb(I0.83Br0.17)3 perovskite formula under adverse ambient conditions. These findings hint at the feasibility of their application in real-world, ambient air conditions, paving the way for their integration into diverse environmental settings, enabling a wider research community to engage in the exciting realm of perovskite solar cell technology.