Short-circuit Current Density Research Articles

Undoped MoOX with oxygen-rich vacancies as hole transport material for efficient indoor/outdoor organic solar cells

Molybdenum oxide (MoOX) films are typically prepared using a thermally-evaporated MoO3 source (ev.MoO3) as the hole transport layer for inverted organic solar cells (OSCs). However, their low conductivity and interface element diffusion severely limit their efficiency and stability. Herein, a novel and effective thermal evaporation method of the MoO2 source to prepare undoped MoOX films with oxygen-rich vacancies and inhibitory atom diffusion properties electrode using ev.MoO2 as the source, is reported. Electron spin resonance analysis indicates that ev.MoO2 has a stronger oxygen vacancy signal peak than ev.MoO3, which contributes to its excellent conductivity. The inverted organic solar cells modified by ev.MoO2 yielded a significant improvement in short-circuit current density (JSC) and fill factor (FF). The power conversion efficiency (PCE) increased from 16.65 % in ev.MoO3 to 17.08 % in ev.MoO2 under AM 1.5 G, which is one of the highest values ever reported for inverted OSCs. Furthermore, owing to the high transmittance and low trap density, the PCE increased from 20.18 % with ev.MoO3 OSC to 22.13 % with ev.MoO2 OSC under 500 lux. In addition, scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy confirmed that ev.MoO2 can prevent the diffusion of Al from the electrode to the functional layers, resulting in a T80 exceeding 800 h under continuous illumination.

Simulation of the absorber layer thickness variation in SnS solar cells using Matlab

The study of thin-film solar cells based on tin sulphide is becoming increasingly relevant due to its advantages over similar technologies, such as its low cost, toxicity, and the fact that its constituent elements are more abundant in the earth's crust; besides, they could be made by thigh vacuum techniques like thermal spraying, sputtering, co-evaporation, or thermal evaporation. On the other hand, Simulations allow modelling of the behaviour of solar cells to understand the processes and improve the device's efficiency. Therefore, in this work, the simulation process is carried out using mathematical models that represent the physical behaviour of the solar cell made of heterojunction of several thin films with ZnO/ZnS/SnS configuration. Two radiation models were evaluated, one using a theoretical equation and the other with data from the incident radiation. Until today, different simulations of solar cells have been carried out mainly using a Solar Cell Capacitance Simulator (SCAPS); however, this research was developed using MATLAB due to its performance and efficiency. The optimal thickness of the absorbent layer was established from the results obtained for open circuit voltage (Voc), short circuit current density (Jsc), fill factor and conversion efficiency (n).

Theoretical exploration of a di-carbazole based dye for 3rd generation dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) are known for their large potential in green, efficient and cost-effective solar energy technology. Therefore, investigating the solar-to-electricity conversion mechanism of photosensitizers in DSSCs can open up a new way for highly effective and stable solar cell devices. In this study, we used different molecular design strategies to develop various D-π-A photosensitizers based on dicarbazole. These approaches involved changing the positions of auxiliary acceptors and π-spacers as well as introducing new π-spacer units. To calculate the physical and electronic properties of these sensitizers, density functional theory (DFT) and time dependent density functional theory (TDDFT) were adopted. FMO analysis showed a significant charge transfer from the donor through the spacer to the acceptor which was also supported by DOS analysis. Energy gap of designed dyes have less than experimental Cz dye. NBO analysis has carried out the bond strength assessment and the studied molecule’s central nitrogen atoms related MOs. All the designed dyes exhibited good nonlinear optical (NLO) properties with maximum linear polarizability 〈α〉 amplitudes higher than first (βtotal) compared to the reference chromophore. Photovoltaic efficiency has been evaluated to electronic (Egap), open circuit voltage (VOC), short circuit current density (JSC), electron injection ability (∆Ginj), electron regeneration (∆Greg) and light harvesting efficiency.

Boosting the effectiveness of a cutting-edge Ca3NCl3 perovskite solar cell by fine-tuning the hole transport layer

Ca3NCl3 has unique electrical and optical properties and shows great potential as an absorber for solar cells, offering a promising solution for enhancing efficiency and reducing costs. To determine the best device layout, this study uses a device combination of Ag/FTO/ETL/Ca3NCl3/HTL/Ni, including seven HTLs and one ETL with the SCAPS-1D simulator. To improve device configuration, consider variables including thickness, temperature, doping density, defect density, and series and shunt resistance. After optimizing device parameters, the Ag/FTO/SnS2/Ca3NCl3/MoO3/Ni device outperformed the other 6-HTLs (Cu2O, CuI, CuSCN, NiO, CuSbS2, and P3HT) based devices with a power conversion efficiency (PCE) of 28.13 %, an open circuit current (VOC) of 1.36 V, a short circuit current density (JSC) of 22.892 mA/cm2, and a fill factor (FF) of 90.36 %. This proposed solar cell has exceptional performance compared to conventional thin-film solar cells, highlighting Ca3NCl3 as an appealing solution for solar energy systems while reducing toxicity issues.

Exchange of Thiol Ligands on CuInS2 Quantum Dots in High Boiling Solvents.

As-prepared quantum dots are covered with long-chain ligands to prevent aggregation. When quantum dots are used in optoelectronic devices such as solar cells and QD-LED, ligand exchange is necessary to replace long-chain ligands with short-chain ones to increase the efficiency of charge transfer from the quantum dots to the electrode. In this study, we successfully exchanged 1-dodecanethiol (DDT) ligands on CuInS2 quantum dots with mercaptopropionic acid (MPA) ligands by using a two-phase system of high-boiling hydrophilic and hydrophobic solvents. The ligand exchange to MPA was achieved by using diethylene glycol (DEG) or ethylene glycol (EG) as the hydrophilic phase and tetradecane as the hydrophobic phase. The ligand exchange rate increased with increasing ligand exchange temperature. When quantum dot sensitized solar cells (QDSSCs) were fabricated using the ligand-exchanged quantum dots, a positive correlation was observed between the progress of ligand exchange and short-circuit current density. This is because charge transfer efficiency from the quantum dots to the TiO2 electrode was improved by the ligand exchange. This work has shown that QDs synthesized using DDT can be applied to optoelectronic devices.

Crystalline silicon solar cell with an efficiency of 20.05 % remanufactured using 30 % silicon scraps recycled from a waste photovoltaic module

Several studies have aimed to develop methods for recycling and recovering valuable materials from waste photovoltaic (PV) modules to keep up with the increasingly stringent waste disposal guidelines. However, silicon (Si) recovered from disposed PV modules is rarely used as a raw material in the solar industry. In this study, 30 % Si recovered from waste PV modules was added to a feedstock to grow a 6inch single-crystalline Si ingot using the Czochralski method. The single-crystalline Si ingot was re-melted and manufactured to produce a higher quality single-crystalline Si ingot with a minority carrier lifetime of 274–1527 μs and purity of 7N7. Thereafter, a Si wafer was manufactured via cropping, squaring, and wafering. Finally, the Si wafer was used to fabricate a solar cell via a conventional process. Solar cell parameters, such as open circuit voltage, short circuit current density, fill factor, and efficiency, were analyzed using a solar simulator. The manufactured solar cell had an efficiency of 20.05 %, which is approximately 0.97 % lower than that of commercial wafer-based solar cells. Moreover, the factors influencing the solar cell efficiency were evaluated.

Highly Efficient Layer-by-Layer Organic Photovoltaics Enabled by Additive Strategy

In this work, layer-by-layer organic photovoltaics (LbL OPVs) were prepared by sequentially spin-coating PM1 and L8-BO solutions. The solvent additive 1,8-diiodooctane (DIO), which has a high boiling point, and solid additive l,3,5-trichlorobenzene (TCB), which has a high volatile, were deliberately selected to incorporate with the L8-BO solutions. The power conversion efficiency (PCE) of LbL OPVs was considerably enhanced from 17.43% to 18.50% by employing TCB as the additive, profiting by the concurrently increased short-circuit current density (JSC) of 26.74 mA cm−2 and a fill factor (FF) of 76.88%. The increased JSCs of LbL OPVs with TCB as additive were ascribed to the tilted-up absorption edge in the long wavelength range and the external quantum-efficiency spectral difference between LbL OPVs with and without TCB as an additive. The molecular arrangement of L8-BO and the PM1 domain was enhanced with TCB as an additive, which was most likely responsible for the increased charge mobilities in the layered films processed with additives. It was indicated that the dynamic film-forming process of the acceptor layers plays a vital role in achieving efficient LbL OPVs by employing additive strategy. Over 6% PCE improvement of the LbL OPVs with PM1/L8-BO as the active layers can be achieved by employing TCB as additive.

The Multi-Functional Third Acceptor Realizes the Synergistic Improvement in Photovoltaic Parameters and the High-Ratio Tolerance of Ternary Organic Photovoltaics.

The ternary strategy proves effective for breakthroughs in organic photovoltaics (OPVs). Elevating three photovoltaic parameters synergistically, especially the proportion-insensitive third component, is crucial for efficient ternary devices. This work introduces a molecular design strategy by comprehensively analyzing asymmetric end groups, side-chain engineering, and halogenation to explore the outstanding optoelectronic properties of the proportion-insensitive third component in efficient ternary systems. Three asymmetric non-fullerene acceptors (BTP-SA1, BTP-SA2, and BTP-SA3) are synthesized based on the Y6 framework and incorporated as the third component into the D18:Y6 binary system. BTP-SA3, featuring asymmetric terminal (difluoro-indone and dichloride-cyanoindone terminal), with branched alkyl side chains, exhibited high open-circuit voltage (VOC), balanced crystallinity and compatibility, achieving synergistic enhancements in VOC (0.862V), short circuit-current density (JSC, 27.52mA cm-2), fill fact (FF, 81.01%), and power convert efficiency (PCE, 19.19%). Device based on D18/Y6:BTP-SA3 (layer-by-layer processed) reached a high efficiency of 19.36%, demonstrating a high tolerance for BTP-SA3 (10-50%). This work provides novel insights into optimizing OPVs performances in multi-component systems and designing components with enhanced tolerance.

Optimizing perovskite solar cell efficiency with Cs0.15FA0.81MA0.04PbBr0.14I2.86 - MAPbBr3 QDs Complex active layer and GuBr interface modified layer

Achieving optimal efficiency in perovskite solar cells (PSCs) necessitates the creation of a light-absorbing layer with superior crystallization, minimal defect concentration, exceptional stability and better energy level alignment. In this context, the active layer of the PSCs comprises (Cs0.15FA0.81MA0.04PbBr0.14I2.86), incorporating MAPbBr3 quantum dots doped with toluene as an anti-solvent to enhance device performance, achieving a Photovoltaic Conversion Efficiency (PCE) of 18.9 %. Furthermore, GuBr is introduced at the interface between NiOx and photovoltaic active layer for effective interface modification. These improvements lead to optimized devices, particularly with GuBr modification at doping amount of 3 mg/ml, showcasing an impressive PCE of 20.6 %. Noteworthy attributes of these devices include a short-circuit current density of 24.7 mA/cm2 and an open-circuit voltage (Voc) value of 1.02 V. Significantly, the altered film retained more than 81 % of its original effectiveness for a prolonged duration surpassing 10 days. The conclusive findings underscore the successful attainment of high efficiency and high stability through the employed design strategy in PSCs.

Fabrication of PSCs with light absorption chips utilizing double-metal-cladding waveguide technology

Metal nanoparticles or periodic metal nanostructures exhibit localized surface plasmon resonance (LSPR) effects, widely employed in photovoltaic devices to enhance the light absorption. In this study, we used a double-metal-cladding waveguide (DMCW) structure to fabricate hexagonal metal nanostructures on the front side of the indium tin oxide (ITO) glass, positioned away from the incident light direction. We then prepared perovskite solar cells under various reaction conditions. The analysis results indicate that the metal nanostructure chip excites near-field coupling, generating strong localized fields, and enhances the light absorption through the LSPR effect. The perovskite solar cells (PSCs) with the chip structures exhibited a significant increase in short-circuit current density (JSC) and fill factor (FF), accompanied by a decrease in dark current, indicating improved photovoltaic characteristics of the cells. Altering the evaporative deposition time of the silver film and the concentration of the reaction solution led to a 12.79% increase in the power conversion efficiency (PCE) of the PSCs.

Synthesis and simulation study of titanium dioxide-based nanomaterial for electron carrier selective contact solar cell

This research introduces a novel approach to synthesizing titanium dioxide (TiO2) nanomaterials using the sol–gel method, specifically aimed at enhancing the performance of Silicon Heterojunction (SHJ) solar cells. The innovation lies in utilizing Iso-Propanol Alcohol and Titanium Tetra Isopropoxides for synthesis, leveraging TiO2’s wide bandgap and low work function to replace the conventional n-doped amorphous silicon layer. This approach is expected to overcome the limitations of traditional materials and significantly improve electron transport efficiency. Advanced characterization techniques were employed to assess the synthesized TiO2 nanomaterials. Atomic Force Microscopy (AFM) measured the roughness and 3D profile, while UV-V spectrophotometry evaluated the absorption properties. The structure and surface morphology were meticulously analyzed using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). These comprehensive analyses ensured a detailed understanding of the nanomaterials’ physical properties. Simulations conducted with the AFORS-HET simulator revealed that TiO2, with a refractive index compatible with a-Si:H(n) and a work function of 4.6 eV, significantly enhances SHJ solar cell performance. The results demonstrated a remarkable 22.57 % improvement in efficiency, achieving an open-circuit voltage (Voc) of 716.8 mV, a short-circuit current density (Jsc) of 37.71 mA/cm2 and a fill factor (FF) of 83.49 %. These findings underscore the potential of TiO2 nanomaterials to revolutionize SHJ solar cell technology by providing a more efficient and effective electron transport layer. Future research will focus on refining the nanostructure of TiO2 further to enhance its photovoltaic applications, aiming to push the boundaries of current solar cell efficiencies even further. This study marks a significant advancement in the field of photovoltaic materials, presenting a novel and promising solution to improving solar energy conversion.

Fabrication of Nano-Carbon-Based Sustainable Perovskite Solar Cells

The rising need for sustainable energy solutions has fuelled considerable research into novel technologies that harness solar energy for efficient and scalable energy storage. Carbon nanotubes (CNTs) have emerged as feasible candidates for these applications due to their unique properties, such as high surface area, better electrical conductivity, and chemical stability.This report focuses on the design and fabrication of cost-effective nano-carbon-based perovskite solar cells (PSCs) and discusses their potential for clean energy generation and storage. This experimental study shows a novel technique to increase the sustainability the conventional fluorine-doped tin oxide (FTO) substrate with an Indium Tin Oxide (ITO) derived from electronic waste and incorporating nanocarbon based-graphene with solution-based techniques. This addition serves as a good basis for the ITO coating, aids charge transport in the perovskite solar cell, and promotes uniform covering maximum electrical conductivity, and transparency. Being the transparent conducting electrode, the CNTs is infused with the upcycled ITO coated glass and was included in the perovskite solar cell architecture, which replaces the traditional ITO electrode, lowering material costs, and improving the circular economy for energy storage devices, and a cleaner energy future.The ITO extraction process entails recovering indium and tin from mobile phones using an environmentally friendly and economical chemical etching process using hydrochloric acid (HCl) to remove the ITO layer. To ensure the purity and structural integrity of the ITO nanoparticles, they were rigorously characterized using X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. After depositing a perovskite- CNTs precursor solution on the ITO layer glass substrate, the light-absorbing layer was annealed. Electron transport and hole-blocking layers were then deposited utilizing solution processing techniques using the PEDOT: PSS and metal electrodes were deposited to complete the device manufacturing. The current-voltage (J-V) relationship was used to compute the open-circuit voltage, short-circuit current density, fill factor (FF), and power conversion efficiency (PCE) of a solar cell. Electrical characterization allow for the calculation of solar cell performance metrics such as short-circuit current (Isc), short-circuit current density (Jsc), and open-circuit voltage (Voc). These findings imply that employing e-waste-derived ITO on graphene substrates to create high-efficiency perovskite solar cells is a realistic option. This research provides a sustainable and cost-effective method for producing high-performance perovskite solar cells by eco-friendly upcycling e-waste for ITO extraction, addressing the critical issue of e-trash management. Keywords Perovskite solar cells, CNTs, sustainable energy, energy conversion.

(Invited) Role of the Energy Offset in the Charge Separation at the Donor: Acceptor Interface

The trade-off between the short-circuit current density and open-circuit voltage has been one of the largest bottlenecks for further improving the device performance of organic solar cells (OSCs). Therefore, understanding the limit to which the energy offset can be reduced and the physics underlying the trade-off relationship is crucial. This study provides a threshold energy that can ensure high charge photogeneration efficiencies for Y-series nonfullerene acceptor-based OSCs and discusses the role of the energy offset in charge separation. In this study, we used transient absorption spectroscopy to track the time evolution of electroabsorption caused by electron-hole pairs generated at donor:acceptor interfaces. We found that an insufficient energy offset led to not only slow charge transfer at the donor:acceptor interfaces, but also inefficient long-range spatial dissociation of the charge transfer states. Our findings highlight the importance of overcoming the trade-off between fill factor and open-circuit voltage for further improving the power conversion efficiency.

Comparison of Pb-based and Sn-based perovskite solar cells using SCAPS simulation: optimal efficiency of eco-friendly CsSnI3 devices.

In this study, we employed the one-dimensional solar cell capacitance simulator (SCAPS-1D) software to optimize the performance of Pb-based and Sn-based (Pb-free) all-inorganic perovskites (AIPs) and organic-inorganic perovskites (OIPs) in perovskite solar cell (PSC) structures. Due to the higher stability of AIPs, the performance of PSCs incorporating Cs-based perovskites was compared with that of FA-based perovskites, which are more stable than their MA-based counterparts. The impact of AIPs such as CsPbCl3, CsPbBr3, CsPbI3, CsSnCl3, CsSnBr3, and CsSnI3, as well as including FAPbCl3, FAPbBr3, FAPbI3, FASnCl3, FASnBr3, and FASnI3, was investigated. SnO2 and Cu2O were selected as an inorganic electron transport layer (ETL) and a hole transport layer (HTL), respectively. CsSnBr₃, CsSnI₃, FASnCl₃, and FASnBr₃ exhibited higher efficiency compared to their Pb-based counterparts. Additionally, most Cs-based perovskites, excluding CsPbI₃, demonstrated better performance relative to their FA counterparts. CsSnI3 AIP device also shows the highest short circuit current density (JSC) of 32.85mA/cm2, the best power conversion efficiency (PCE) of 16.00%, and the least recombination at the SnO2/CsSnI3 interface. The thickness, doping, and total defect density of CsSnI3 PSC have been systematically investigated and optimized to obtain the PCE of 17.36%. These findings highlight the potential of CsSnI3 PSCs as efficient and environmentally friendly PSCs.

Bithieno[3,4-c]pyrrole-4,6-dione-Based Wide-Bandgap Donor Polymers for Efficient Polymer Solar Cells.

The polymer solar cells (PSCs) have garnered substantial interest owing to their lightweight, cost-effectiveness, and flexibility, making them ideal for large-scale roll-to-roll manufacturing. In this study, two wide-bandgap (WBG) donor polymers, PFBiTPD and PClBiTPD, utilizing bithieno[3,4-c]pyrrole-4,6-dione (BiTPD) as the electron-accepting unit and fluorinated/chlorinated benzo[1,2-b:4,5-b']dithiophene (BDT) as the electron-donating moiety are designed and synthesized. The polymers demonstrated large optical bandgaps (exceeding 1.80eV) and are blended with ITIC-4F to form the active layers in PSCs. The PFBiTPD-based devices showed a well-dispersed fibrillar network, facilitating efficient charge generation and transport. Thus, these devices attained a power conversion efficiency (PCE) of 8.60%, featuring a fill factor (FF) of 62.89%, an open-circuit voltage (Voc) of 0.88V and a short-circuit current density (Jsc) of 15.54mA cm-2. In contrast, PClBiTPD-based devices displayed lower performance due to less favorable morphology. The study underscores the importance of polymer design and morphology control in optimizing the photovoltaic performance of PSCs.

Dispersion of hydrophobic conductive carbon black (CB) in polytetrafluoroethylene (PTFE) emulsion through liquid bridges and fabrication of PTFE/CB composite film for triboelectric nanogenerators

Polytetrafluoroethylene (PTFE) is a highly electronegative material that is widely used in Triboelectric nanogenerators (TENGs). However, due to the ultralow surface energy of PTFE, it is difficult to achieve a stable and even dispersion of hydrophobic carbon black in the PTFE emulsion. In this study, a novel method was used to achieve a stable and uniform dispersion of hydrophobic carbon black in the PTFE emulsion. An interfacial modifier was added to form liquid bridges between PTFE emulsion particles. The hydrophobic carbon black was then dispersed among these liquid bridges, resulting in its uniform distribution within the aqueous emulsion. The addition of 0.75 wt% CB resulted in a 4.6-fold increase in open-circuit voltage and a 3.5-fold increase in short-circuit current density compared to pure PTFE. Moreover, after 10000 cycles, the open-circuit voltage remained mostly unchanged, indicating that it has great potential for use in wearable devices.

Dual photoelectrode-drived Fe–Br rechargeable flow battery for solar energy conversion and storage: A cost-effective approach

The integrated design of solar energy conversion and storage systems has attracted increasing attention, and non-spontaneous redox reactions driven by dual photoelectrodes provide a potential solution to this issue. This study presents a solar rechargeable flow battery (SRFB) that combines dual photoelectrodes (BiVO4 or Mo–BiVO4 as photoanode, polyterthiophene (pTTh) as photocathode) with cost-effective redox pairs (Fe3+/Fe2+ and Br3−/Br−). The system charges under simulated solar illumination (100 mW∙cm−2, AM 1.5G) and releases stored energy controllably as electrical energy. Research indicates the Mo–BiVO4 photoanode and pTTh photocathode achieve an open-circuit voltage of 0.34 V and a short-circuit current density of 0.38 mA cm−2. Using a specially designed Fe3+/Fe2+-Br3−/Br− (Fe–Br) SRFB device made via 3D printing, a charging photocurrent of approximately 1.9 mA cm−2 is attained. In constant current discharge tests, an initial discharge voltage of 0.23 V is observed at 0.1 mA∙cm−2 within the 10 discharge cycles, demonstrating system stability and offering a viable solution for low-cost, large-scale solar energy storage and conversion.

Comparative examination of both spectral properties and hybrid solar cell application of 2,4,6-trimethoxyphenoxy substituted phthalocyanine dyes

In this study, novel octa 2,4,6-trimethoxyphenoxy substituted phthalocyanines, and tetra chloro and tetra 2,4,6-trimethoxyphenoxy substituted phthalocyanines were synthesized, characterized, examined their spectral properties comparatively and investigated of hybrid solar cell application of them. The spectral characterizations can be performed for all phthalocyanine compounds, solar cell application was only possible for tetra chloro tetra 2,4,6-trimethoxyphenoxy substituted phthalocyanines, the others phthalocyanines not due to their low yield.Solar cell properties of the tetra chloro tetra 2,4,6-trimethoxyphenoxy substituted phthalocyanines were studied using the ITO/ZnO/C60/ P3HT /LiF/Al structure. In order to improve and compare performance parameters of the poly(3-hexylthiophene) (P3HT) based solar cells, the tetra chloro tetra 2,4,6-trimethoxyphenoxy substituted H2Pc (2), Co(II)Pc (3) and Ni(II)Pc (4) compounds were incorporated individually into the solar cell structure between ZnO and C60 layers in which amorphous ZnO nanoparticles serves as electron transfer layer. Solar cell performance parameters such as short circuit current density (JSC), open circuit voltage (VOC), fill factor (FF) and power conversion efficiency (η) were studied as comparison parameters. Incorporation of Ni(II)Pc (4) into the reference structure between ZnO and C60 caused an increase 23.4 % in Jsc and 4.4 % in η whereas incorporation of Co(II)Pc (3) layer into the reference structure caused an increase 135.0 % in Jsc and 107.0 % in η under an illumination of 100 mW/cm2 with an AM 1.5G solar simulator. The best JSC and η (%) values were obtained for P3HT based solar cells with Co(II)Pc (3) interlayer.

Configurational design of NiPc derivative as electron transport material for stable and efficient perovskite solar cell: DFT and SCAPS-1D framework

In the present work electron transport layer is optimized to achieve the high stability and efficiency of Formamidinium tin iodide (FASnl3) perovskite solar cells (PSCs). Optical and electronic characteristics of designed ETLs were investigated by implying density functional theory. The designed ETLs show improved charge mobility over the nickel phthalocyanines (NiPcs). It has been observed that NiPc, a material for a hole-hole-transporting layer, acts as an electron transport layer in a modified configuration implying electron-withdrawing groups on the hydrogen site. In this study, the electron-withdrawing group (F−, Cl−, Br−, and I−) were substituted in the configuration X8Y8 (X and y are halide ions where X ≠ Y). Among various configurations, F8Br8NiPc demonstrates the maximum charge mobility 50 cm2/Vs Furthermore, the designed ETLs show improved stability over the NiPcs, due to their hydrophobic nature. Optimal characteristics for both the HTL and ETL were achieved to ensure enhanced efficiency. Furthermore, to investigate the impact of various parameters such as thickness, doping density, and defect density of the ETL layer SCAPS-1D numerical simulation was employed. The obtained electron affinity for designed HTL and ETL were found to be 2.4 eV and 4.247 eV respectively. The optimized photovoltaic (PV) characteristics including power conversion efficiency, short-circuit current density (Jsc), and open-circuit voltage (Voc) were found as 30.58 mA/cm2, 1.09 V, and 29.12 % respectively.

Semiconductor heterojunctions coated with reduced graphite oxide as electron transfer materials for high-performance perovskite solar cells

Exploring and insight into the relationship between the microstructure, light absorption performance, and carrier transport of perovskite light absorption layer materials and carrier transport layer materials is crucial for obtaining efficient and stable perovskite solar cells. We adopted a simple strategy to prepare a composite material known as reduced graphene oxide wrapped mesoporous hierarchical TiO2–CdS semiconductor heterojunctions (TiO2–CdS-RGO) as the electron transport layer in formamidine lead iodide perovskite solar cells. Compared with single TiO2 and binary composite, this composite material exhibits enhanced photoluminescence quenching, reduced photo generated carrier recombination rate, and improved electron transfer capability. Photovoltaic devices based on TiO2–CdS-RGO composite material showed a 14.5 % increase in short-circuit current density (JSC) and a 36.3 % increase in photoelectric conversion efficiency (PCE) compared to those with only TiO2. The improved optoelectronic properties observed with the TiO2–CdS-RGO as electron transfer layers can be attributed to several factors. On the one hand, mesoporous TiO2 with a high specific surface area is beneficial for perovskite infiltration and enhances electron transfer rate. On the other hand, the well-matching energy level structure among the three components aids in electrons extraction and reduces the recombination rate of photo generated charge carriers; In addition, RGO nanosheets with high conductivity serve as an efficient electron transfer network, providing a rapid charge transfer pathways, which is crucial for enhancing the photoelectric conversion performance of perovskite solar cells.