Front Contact Research Articles

Boosting Efficiency in Flexible Perovskite Solar Cells with Novel HTLs and ETLs: A drift‐diffusion numerical study of CBz‐PAI Interlayers and MXene Back Contacts

AbstractIn this study, the functioning of flexible perovskite solar cells (FPSCs) is examined using drift‐diffusion SCAPS‐1D simulations under ideal conditions. The focus is on the CBz‐PAI interlayer at the perovskite and hole transport layer (HTL) interface and the impact of innovative materials for HTLs, electrons transport layers (ETLs), and transparent conduction electrodes (TCOs), such as AZO and MXene, in the front and back contacts. Initially, 50 configurations of ETLs, including BaZrS3, SnS2, STO, WS2, and ZrS2, as well as HTLs such as ACZTSe, CuBiS3, CZGS, and D‐PBTTT‐14, are tested to identify optimal architecture for enhancing device efficiency. The incorporation of the CBz‐PAI interlayer effectively reduces interfacial charge recombination, minimizing VOC losses and boosting overall performance. After further optimization and the integration of MXene as a back contact, the final FPSC design (PET/ITO/AZO/ZrS2/(FAPbI3)0.77(MAPbBr3)0.14(CsPbI3)0.09/CBz‐PAI/CZGS/MXene‐V3C2F2) achieves an impressive PCE of 27.17%, setting a new benchmark for FPSC efficiency.

A comprehensive SCAPS-1D simulation study on the photovoltaic properties and efficiency enhancement of CH3NH3PbCl3 perovskite solar cells

Abstract Recent progress in lead (Pb) halide perovskites has inspired much research into economical solar cells, focusing on critical issues of stability and toxicity. This study investigates the performance of perovskite solar cells (PSCs) by simulating the impact of a methylammonium lead chloride (CH3NH3PbCl3) layer as the absorber material using the SCAPS-1D simulator. The first comprehensive study of this material examines the role and configuration of the Electron Transport Layer (ETL) and Hole Transport Layer (HTL), as well as the absorber layer, on solar cell performance. The ETLs used in the device optimization are ZnO, SnO2, IGZO, and CdS; the HTL is CuO; and the front and back contacts are Au and Ni, respectively. The study highlights CuO as the optimal HTL for CH3NH3PbCl3, delivering power conversion efficiencies (PCEs) of 16.10%, 16.06%, 16.05%, and 14.41% with ZnO, SnO2, IGZO, and CdS as ETLs, respectively. The performance of these device architectures is significantly influenced by factors such as defect density, absorber layer thickness, ETL thickness, and the combination of different ETLs and CuO HTLs. Furthermore, this study elucidates the impact of absorber and HTL thickness on key photovoltaic parameters, such as VOC, JSC, FF, and PCE. Also, we have discussed the VBO, and CBO for different ETLs. Additionally, we examine the effects of series and shunt resistance, operating temperature, quantum efficiency (QE), capacitance-voltage characteristics, generation and recombination rates, and current density-voltage (J-V), analysis of absorption data, and impedance analysis behavior on achieving the highest efficiency of the device. This comprehensive study provides critical insights into designing cost-effective, high-performance PSCs, and advancing the development of next-generation photovoltaic technologies.

Optimizing Cs2CuBiBr6 double halide perovskite for solar applications: the role of electron transport layers in SCAPS-1D simulations.

Perovskite solar cells are commonly employed in photovoltaic systems because of their special characteristics. Perovskite solar cells remain efficient, but lead-based absorbers are dangerous, restricting their manufacture. Therefore, studies in the field of perovskite materials are now focusing on investigating lead-free perovskites. The SCAPS-1D simulator is used to simulate the impact of lead-free double perovskite as the absorber in perovskite solar cells. The research examines how the effectiveness of solar cells is impacted by a hole transport layer (CBTS) and several electron transports layers (WS2, C60, PCBM, and TiO2), using Ni and Al acting as the back and front contacts metal. This work explores the impact of a Cs2CuBiBr6 perovskite as a solar cell absorber. The effectiveness of these device structures depends on defect density, absorber thickness, ETL thickness, and ETL combination. With WS2, C60, PCBM, and TiO2, the device's power conversion efficiency (PCE) is 19.70%, 18.69%, 19.52%, and 19.65%, respectively. This research also highlights the impact of the absorber and HTL thickness. This investigation further included the analysis of the valence band offset (VBO) and conduction band offset (CBO). We also investigated the current density-voltage (J-V), quantum efficiency (QE), series and shunt resistance, capacitance-Mott-Schottky characteristics, and photocarrier generation-recombination rates and effective temperature. This study provides crucial structural design guidelines for a lead-free double perovskite device and highlights solar energy optoelectronic developments.

Achieving 32.9% efficiency in Pb-Based quantum dot solar cells via SCAPS-1D simulation optimization

Abstract This study presents a comprehensive investigation and in-depth analysis of the optimization of Pb-based quantum dot solar cells (QDSCs), concentrating on the influences of doping concentration, absorber layer thickness, defect density, temperature, and resistive elements. We systematically examined three absorber materials: lead sulfide (PbS), tetrabutylammonium iodide-treated PbS (PbS-TBAI), and lead selenide (PbSe) quantum dots (QDs). Optimal doping concentrations of 1 × 10 17 cm−3 for PbS and 1 × 10 22 cm−3 for both PbS-TBAI and PbSe were identified. Our findings reveal that precise control of these parameters can significantly enhance power conversion efficiency (PCE), achieving values of 24.6%, 28%, and 26.2% for PbS, PbS-TBAI, and PbSe, respectively. Additionally, we investigated the impact of absorber layer thickness on device performance. We discovered that a 1 µm thickness for PbS yields a maximum PCE of 32.9% due to balanced photon absorption and reduced Shockley–Read–Hall recombination. Conversely, PbSe’s performance declined with increased thickness because of its layer-dependent bandgap. We found that lower defect densities ( 1 × 10 14 cm−3) critically improve PCE and fill factor across all materials. The temperature-dependent studies demonstrated that PbS-TBAI exhibits remarkable resilience, maintaining efficiency under thermal stress due to effective surface passivation. Analyses of series and shunt resistances highlighted the importance of minimizing internal resistances to optimize device performance. The proposed device structure comprises a fluorine-doped tin oxide front contact layer, a silver sulfide (Ag2S) electron transport layer, the QD absorber layer (PbS, PbS-TBAI, or PbSe), and copper(I) oxide (Cu2O) hole transport layer. Utilizing cascade band alignment, we achieved a record PCE of 32.9%. This research highlights the significant potential of Pb-based QDSCs for achieving high efficiencies through promising material and structural optimization, positioning them as competitive candidates for next-generation solar technologies. The results provide a valuable understanding of designing high-performance QDSCs, paving the way for their integration into sustainable energy solutions.

Recycling of Photovoltaic Modules – A Strategy for Silicon and Metal Contact Recovery

As the installed capacity of photovoltaic (PV) systems continues to grow, also does the necessity to address the accumulating waste from decommissioned PV modules. Millions of modules will need to be retired in the next few decades, and this poses a challenge that requires the development of cost-effective and efficient recycling strategies, with a focus on essential components such as solar cells, which are known for their significant environmental impact and energy budget. This study explores strategies to recover metal from front and rear contacts, as well as the potentiality of silicon substrate recrystallization. Alkaline-organic solutions allow for complete metal detachment with small-to-minimal silicon loss, and recrystallization of recovered substrates provides promising results in obtaining wafers suitable for the newly established industry requirements. Al-BSF solar cells fabricated from recycled materials exhibit improved performance, proving the feasibility of reclaiming precious metals and silicon substrates from PV modules. These encouraging first results represent an important step towards cycling PV systems within a circular economy framework, thereby minimizing waste and maximizing resource utilization.

Enhancing performance of antimony selenide solar cell with different back surface field configurations

Abstract This study focuses on optimization of solar cells using antimony selenide (Sb2Se3) as absorber layer. A novel solar cell structure, designed and simulated with configuration ZnO/i-ZnO/Sb2Se3/NiO or SnS, demonstrates a notable efficiency improvement. The performance of this solar cell was rigorously evaluated using the SCAPS simulation tool. Key structural parameters were optimized as follows: ZnO at 30 nm, i-ZnO at 20 nm, Sb2Se3 as active layer at 100 nm, and NiO at 20 nm. NiO & SnS, utilized as a back surface field (BSF), effectively minimizes recombination. Various parameters were analyzed, including the band diagram, thickness, bandgap, doping concentration, effect of concentration on electric field, recombination and generation rates, temperature effects, and series and shunt resistance of proposed structure. The proposed model achieved an efficiency of up to 31.4%, highlighting the potential of NiO & SnS as BSF in antimony selenide solar cells. The metal work functions for front and back contacts are 4.4 eV and 5.1 eV respectively. This breakthrough suggests a transformative path toward significantly enhanced solar cell performance, showcasing the latent potential of NiO BSF in optimizing Sb2Se3-based solar cells.

Enhancing the Efficiency of PM6:Y6 Bulk-Heterojunction Organic Solar Cells through SCAPS Simulation Optimization

Organic solar cell (OSC) is becoming a point of attraction in the solar cell industry due to their benefits, such as light weight, flexibility, low cost, semi-transparency, and easy fabricating methods. By replacing fullerene with non-fullerene acceptors like Y6, ITIC, PCBM, and ICBA, the power conversion efficiency (PCE) of OSCs has surpassed the 15% benchmark. Here, the proposed OSC structure includes an ITO front contact electrode, SnO2 electron transport layer (ETL), PM6:Y6 active layer, Cu2O hole transport layer (HTL), and Ag back contact electrode. Systematic numerical simulation of the above proposed OSC has been performed using a solar cell capacitance simulator (SCAPS)-1D (Version 3.3.09). The device improvement analysis has been carried out in steps by analyzing the ETL-HTL effect, selecting the optimum thickness of the active layer, and the optimum value of defect density. In the first step, a PCE of 24.60% was achieved, followed by an improvement to 27.55% with the optimized defect density value. The best PCE of 27.74% was achieved in the third step with an optimized active layer thickness, leading to high fill factor (80.56%), open-circuit voltage (0.9461 V), and short-circuit current density (36.188 mA/cm2). These simulated results promote an in-depth understanding of the optical and electronic properties of PM6:Y6 blend-based OSC and show the potential of NFA-BHJ OSCs as promising candidates for solar cells in the near future.

Novel Front Contacts for Hydrophobic Gas Diffusion Layers Enable High Energy Efficiency and Durability for Electrochemical CO2 Reduction to C2+ Products.

Electrochemical CO2 reduction (eCO2R) is an attractive route to mitigate the rise in the global CO2 concentration while producing value-added chemicals. Ethylene (C2H4) is one such product of eCO2R which is an essential industrial precursor with a prominent global market of $230 billion. The large-scale implementation of C2H4-selective CO2 electrolyzers is still challenge due to the low energy efficiencies causes by high ohmic resistances when either employing a hydrophobic gas diffusion layer such as expanded polytetrafluoroethylene (ePTFE), or employing a near neutral catholyte in a single-gap electrolyzer. In this work, we have developed a novel front contact for a CO2 electrolyzer in a zero-gap architecture for electrically insulating gas diffusion layers. This front contact layer allows for incorporating an ePTFE gas diffusion layer while achieving similar full cell voltages as carbon-based gas diffusion electrodes; this configuration also has the added benefits of increased cell stability and selectivity for ethylene. By tailoring the catalyst layer, gas diffusion medium, and operating conditions for a zero-gap ePTFE gas diffusion layer, we were able to achieve a full cell voltage of 2.5 V, with faradaic efficiencies of 48% for ethylene and over 90% faradaic efficiency for reduced carbon species at 200 mA cm-2 and 25 cm2 geometric area cell. This work points towards strategies for developing a scalable, stable, and high energy efficiency eCO2R for C2+ products.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Electrolytic Silver Recovery from Photovoltaic Waste

As an increasing number of photovoltaic (PV) systems reach end of life, there is a growing need to develop a process to keep critical materials in the supply chain. Currently, the processing cost of recycling solar panels exceeds the value of raw materials being collected. While there are many ways to approach this problem, one standout method is to improve silver recovery efforts. Silver, which is used as the fingers on the front contact, makes up less than 1% of the total mass of decommissioned systems while constituting approximately 40% of the value of the raw materials. Mechanical separation techniques have been generally successful in extracting the silver, but the product is still low in concentration and recyclers encounter significant processing fees from off takers. In this talk, a chemical leaching process in conjunction with an electrochemical recovery system will be discussed as a means of extracting high purity silver from recycled PV materials. Classically, electroplating processes utilize solutions containing metals at concentrations >10 g/L. In this case, the expected concentrations are less than 2 g/L, and maintaining high yields will require the electrochemical device to operate at concentrations on the order of 100s of ppm. Mass transport limitations will be mitigated by the development of a flow-through 3D cathode architecture, which will allow the system to operate at lower concentrations without requiring the application of higher cell potentials that would decrease selectivity and subsequently lower the purity of the recovered silver product. The performance of these devices will be explored in conjunction with auxiliary system components and controls that will be integrated to yield an automated system for silver powder recovery. Figure 1

Downshifting Encapsulant: Optical Simulation Evaluation of the Solution to Ultraviolet‐Induced Degradation in Silicon Heterojunction Solar Cells

Ultraviolet (UV)‐induced degradation (UVID) poses a significant challenge for the prospective mass production of silicon heterojunction (SHJ) solar cells, known for their high efficiency. In this study, the magnified impact of UV radiation when employing a silicon carbide (SiC)‐based transparent passivating contact (TPC) on the front side of SHJ solar cells is reported. A reduction in open‐circuit voltage (VOC), short‐circuit current (JSC), and fill factor of 12%, 6%, and 11%, respectively, is observed after UV exposure. Conventional UVID mitigation measures, UV‐blocking encapsulation, are assessed through single‐cell TPC laminates, revealing an unavoidable tradeoff between current loss and UVID. Alternatively, the utilization of ultraviolet‐downshifting (UV‐DS) encapsulants is proposed to convert UV radiation into the visible light spectrum. An optical simulation method, conducted via OPAL2, is presented to evaluate UV‐DS encapsulants for diminishing UVID in SHJ solar cells with different front contacts. A simple methodology is proposed to mimic the optical property of UV‐DS encapsulants. In the simulation results, additional current gains of up to 0.33 mA cm−2 achievable with suitable UV‐DS encapsulants are highlighted. The factors related to the UV‐DS effects are evaluated and the optimization pathway for UV‐DS encapsulants is elucidated.

Interpretation of the degradation and trends in the performance of heterojunction silicon solar cells at low temperature

A compact model that combines numerical simulations using AFORS-HET and accurate equivalent circuit modelling is proposed and used to interpret the origins of the degradation and anomality's in the performance of the a-Si:H/c-Si heterojunction solar cells and its parameters at low temperature. The interpretations are applied to several trends reported on real cells. It is shown that as T decreases the a-Si:H(i) layer is depleted gradually from holes and that the cell operation fails once the layer is totally depleted and becoming intrinsic. The failure is caused by a substantial and sharp increase in the cell series resistance causing the collapse of the fill factor and of the cell current. It is found that at low temperature the open circuit voltage is significantly affected and its temperature dependence strongly distorted by hole depletion in the a-Si:H(i) spacer especially when the TCO work function is not appropriate. It is aslo shown that the S-shape in the cell I-V characteristics under illumination is closely linked to the TCO barrier reverse saturation current which explains its higher probability of appearnce at low temperature. Finally, it is concluded that the HJT cell would perform optimally down to the low 200 K range when the a-Si:H(p) is heavily doped and the front contact is ideally ohmic. Failing to satisfy such conditions the temperature range in which the HJT cell is useful is very limited.

Validation of a phase-field approach for contact line hysteresis against a sloshing droplet case

AbstractUnderstanding liquid propellants behavior in microgravity conditions is critical for efficient spacecraft design. For a number of operations, ranging from engine restart to orbital propellant storage and transfer, insight is needed to characterize capillary-dominated flows. In such conditions, surface tension and wetting properties, including contact angle hysteresis, can greatly impact the fluid’s behavior and therefore spacecraft performance. Using experimental data from ESA Propulsion Laboratory, a contact line model for the Cahn–Hilliard phase-field method is validated. The case studied is that of a droplet confined between two oscillating plates, which aims to isolate and observe contact angle-driven physics, limiting the effect of gravity on the flow in a simple and reproducible way on ground. The contact line model allows for the prediction of contact line motion without requiring the computation of dynamic contact angles or contact line velocities, thus simplifying implementation and reducing computational overhead. For the validation, contact line pinning and motion under varying oscillation frequencies is investigated. Specifically, the length between the rear and front contact line edges, as well as the shape of the sloshing droplet are compared. The results show good agreement between simulations and experimental data, confirming the model’s accuracy in predicting contact line behavior and pinning.

Numerical study of P3HT-based hybrid solid-state qantum dot solar cells with CdS quantum dots employing different metal oxides using SCAPS-1D

This study presents a comprehensive numerical investigation into solid-state quantum dot solar cells (SSQDSCs) utilizing P3HT poly(3-hexylthiophene) as both a hole transport and absorber layer employing SCAPS-1D simulation software, the research explores the performance of cells composed of FTO (Fluorine-doped Tin Oxide) as the front contact, integrated with different metal oxides (Titanium dioxide (TiO2), zinc oxide (ZnO), and tin dioxide (SnO2), CdS (Cadmium sulfide )quantum dots, P3HT, and Pt (platinum )as the back contact namely Hybrid solar cell. The thickness of each layer is systematically optimized, and the influence of various CdS quantum dots sizes is thoroughly examined. The study also dived into the characterization of interface defects at the P3HT/CdS junction, involving modifications to the electron affinity of P3HT. Additionally, the impact of metal work function variations was also investigated analyzing at each case critical parameters such as open-circuit voltage (VOC), short-circuit current density (JSC), fill factor (FF), power conversion efficiency (PCE) and quantum efficiency. The results demonstrate that optimization of these parameters has the potential to elevate solar cell efficiency to 18%. These simulation findings offer valuable insights for comparative analysis and a deeper understanding of the challenges encountered in experimental research.

Performance optimization of MA0.5FA0.5PbI3/CsPbI3 based hybrid perovskite solar cell emphasizing on double absorber layer

Abstract The utilization of cesium-based lead halide (CsPbI3) PSC has considerable potential in the photovoltaic industry due to their high efficiency, underpinned by features such as a high absorption coefficient, thermal stability, and commendable efficiency. Nevertheless, the bandgap of CsPbI3, standing at 1.7 eV, poses a challenge as it is relatively high for a single-junction device. To overcome this limitation, we introduced a dual absorber layer structure by interleaving CsPbI3 with a lead-based hybrid perovskite material, denoted as MA0.5FA0.5PbI3. This investigation focused on the MA0.5FA0.5PbI3/CsPbI3 hetero-junction structure to ascertain the maximum possible efficiency. Therefore, this study proposed a PSC with the configuration of Ag/MoO3/MA0.5FA0.5PbI3/CsPbI3/IGZO/Au. In this setup, MoO3 (Molybdenum Trioxide) is used as the HTL and IGZO (Indium Gallium Zinc Oxide) as the ETL. Silver (Ag) serves as the back contact and gold (Au) is the front contact. This device demonstrated remarkable characteristics with Voc = 1.307 V, Jsc = 22.71 mA cm−2, FF = 86.58%, and η = 26.21%, showcasing a substantial improvement compared to previously reported CsPbI3-based homojunction PSCs. Furthermore, this study delved into the effects of absorber doping, absorber material thickness, bulk defect, and interfacial defects on solar cell parameters to obtain high-performance solar cells.

Solar Cells: Applications and Current Opinion

Due to the manufacturing process, silicon-based solar cells have conquered the marketplace, but their cost is not economic. As a result, thin-film manufacturing was done with low-cost, appealing materials generated using less expensive, scalable, and manufacturable procedures. The motivation behind this work is to develop low-cost, high-efficiency solar cells using chemical and electrochemical techniques. Thin film solar cell structure could be presented as glass, Cu structure, CdS window material, TCO, and CdTe absorber material. The absorber and window materials include layers such as CdS and CdTe, while Cu and TCO are the back and front contacts. By using CSS and chemical bath deposition (CBD), The usual method of making this structure is to grow window (CdS) and absorber (CdTe) materials. CBD is a batch method that generates enormous quantities of Cd-containing waste solutions each time, adding to the production process's high cost. Sputtering or PVD, including high vacuum conditions, is performed with back and front contacts. This research program focuses on developing an "all chemical-solar cell" structure. This study showed that CdS and CdTe materials may be employed and electrodeposited in thin-film solar cell systems, CBD and electroless techniques. Furthermore, the back and front contacts can be coated using the CdS electrolytic bath, which is utilized for seven months without being discarded, but the CBD bath lasts 2-3 days. The deposition rate of the thin films was about 50 - 100 times greater than reported values in the literature. The efficiency of the manufactured cells was between 1 and 6%, which was reduced by the duration of time. Twenty days after manufacturing a TCO, CdS, CdTe, the short-circuit current, Cu-Ag solar cell, and open-circuit voltage deposited by all chemical and electrochemical deposition techniques were 0.8 mA/cm2 and 8.8 mV, respectively. However, consistency and reproducibility remain unresolved. The growth of CdTe nanocrystalline thin film is one of the reasons it has been identified as having nanosized tracks. High-quality CdTe layers should be developed, or in cadmium solar cells, its layered structure is the form of a cadmium window and a zinc oxide buffer layer to increase the consistency of the solar cell efficiency.

Optimization of Sr3NCl3-based perovskite solar cell performance through the comparison of different electron and hole transport layers

Strontium Nitride Trichloride (Sr3NCl3) is a promising absorber material for solar cells due to its unique structural, electrical, and optical properties. We conducted a thorough investigation to scrutinize the structural, optical, and electronic characteristics and the photovoltaic efficiency of double-heterojunction solar cells utilizing Sr3NCl3 absorbers. Various metals were evaluated for the front and rear contacts to determine the optimal metal-semiconductor interface, with the study determining that silver (Ag) is the most suitable option for the front contact and nickel (Ni) for the back contact. The PV performance of innovative Sr3NCl3 absorber-based cell structures was evaluated with two different Hole Transport Layers (HTLs), MASnBe3 and CBTS, alongside ZnO and WS2 serving as the transition metal dichalcogenide (TMD) Electron Transport Layers (ETLs). This investigation examined a range of factors, such as layer thickness, operational temperature, doping density, defect densities at both the interfaces and within the bulk, carrier generation and recombination rates, quantum efficiency (QE), series versus shunt resistance, absorption coefficient, and current density-voltage (J-V) characteristics, utilizing the SCAPS-1D simulator software. Fine-tuning of both two HTL and ETL revealed that the highest power conversion efficiency (PCE) of 27.34 % with JSC of 19.78 mA/cm2, fill factor (FF) of 88.84 %, and VOC of 1.56 V was achieved with MASnBe3 HTL and ZnO ETL, while the lowest PCE of 25.55 %, with JSC of 19.77 mA/cm2, FF of 89.07 %, and VOC of 1.45 V was obtained for CBTS HTL and WS2 ETL, respectively. These findings highlight the promising potential of Sr3NCl3 absorbers with ZnO as ETL and MASnBe3 as HTL for developing advanced perovskites heterostructure solar cells for enhanced performance in the future.

In Situ IR Spectroscopy Studies of Atomic Layer-Deposited SnO2 on Fullerenes for Perovskite Photovoltaics.

In recent years, atomic layer deposition (ALD) has established itself as the state-of-the-art technique for the deposition of SnO2 buffer layers grown between the fullerene electron transport layer (ETL) and the ITO top electrode in metal halide perovskite-based photovoltaics. The SnO2 layer shields the underlying layers, i.e., the fullerene-derivative materials such as C60 and PCBM, as well as the perovskite absorber, from water ingress and damage induced by the sputtering of the transparent front contact. Our study undertakes a comprehensive investigation of the impact of SnO2 ALD processing on fullerenes by means of in situ spectroscopic ellipsometry (SE) and transmission infrared spectroscopy (FTIR). While no difference in SnO2 bulk properties is observed and the perovskite absorber degradation is nearly entirely avoided during exposure to heat and vacuum, when the absorber is introduced beneath the organic ETLs, a SnO2 growth delay of about 50 ALD cycles is measured on PCBM, whereas the delay is limited to 10 cycles in the case of growth on C60. Notably, FTIR measurements show that while C60 remains chemically unaffected during SnO2 ALD growth, PCBM undergoes chemical modification, specifically of its ester groups. The onset of these modifications corresponds with the detection of the onset, after the initial delay, of ALD SnO2 growth. It is expected that the modification that the PCBM layer undergoes upon ALD SnO2 processing is responsible for the systematic lower photovoltaic device performance in the case of PCBM-based devices, with respect to C60-based devices.

Photovoltaic performance in CIGS solar cells: effects of using Mg- and Al-doped ZnO thin-film layers as alternative TCO and front contact layer

Photovoltaic performance in CIGS solar cells: effects of using Mg- and Al-doped ZnO thin-film layers as alternative TCO and front contact layer

Optimization of laser patterning process for eco-friendly tin-halide perovskite solar module – with a nanosecond green laser

The tin-based perovskite solar cells are promising future eco-friendly photovoltaic technology with increasing efficiency, which relies on fluorine-doped tin oxide (FTO) or indium tin oxide (ITO) as a transparent conducting oxide (TCO) for front contact. In the monolithic module fabrication process interconnections are executed by a series of three scribes with two different lasers 1064 nm and 532 nm. This study aims to simplify the interconnection process in tin-based perovskite solar modules by using a single visible laser source to perform all three scribes. The study uses an inverted device structure of Glass/TCO/ Poly(3,4-ethylenedioxythiophene): Polystyrene sulfonate (PEDOT: PSS)/Formamidinium-tin-iodide (FASnI3)/C60/Bathocuproine (BCP)/Ag and a 532 nm nanosecond pulsed laser source to pattern the ITO and FTO (P1 scribe), the PEDOT: PSS/FASnI3/C60/BCP stack (P2 scribe), and the PEDOT: PSS/FASnI3/C60/BCP/Ag (P3 scribe). The quality of the P1 scribe is assessed by examining the edges, completeness of film removal, cracking, film delamination, and elemental mapping using a stylus profiler, optical microscope, and energy dispersive x-ray spectroscopy. The P1 scribe is completely removed with line widths of 70 µm and 110 µm of ITO and FTO, respectively, without damage to the glass substrate. The profiles are steep, and the electrical isolation is greater than 40 MΩ. The same 532 nm laser is used for P2 and P3 scribes. The ablation of PEDOT: PSS during P2 and P3 scribe is studied by Raman spectroscopy. The results show that the use of a single 532 nm laser source can simplify the patterning process of monolithic tin-based perovskite solar modules, and potentially reduce production costs.

Universal droplet propulsion by dynamic surface-charge wetting

Controllable droplet propulsion on solid surfaces plays a crucial role in various technologies. Many actuating methods have been developed; however, there are still some limitations in terms of the introduction of additives, the versatilities of solid surfaces, and the speed of transportation. Herein, we have demonstrated a universal droplet propulsion method based on dynamic surface-charge wetting by depositing oscillating and opposite surface charges on dielectric films with unmodified surfaces. Dynamic surface-charge wetting propels droplets by continuously inducing smaller front contact angles than rear contact angles. This innovative imbalance is built by alternately storing and spreading opposite charges on dielectric films, which results in remarkable electrostatic forces under large gradients and electric fields. The method exhibits excellent droplet manipulation performance characteristics, including high speed (~130 mm/s), high adaptability of droplet volume (1 μL–1 mL), strong handling ability on non-slippery surfaces with large contact angle hysteresis (CAH) (maximum angle of 35°), significant programmability and reconfigurability, and low mass loss. The great application potential of this method has been effectively demonstrated in programmable microreactions, defogging without gravity assistance, and surface cleaning of photovoltaic panels using condensed droplets.