Structure Perovskite Solar Cells Research Articles

Formamidinium Lead Iodide‐Based Perovskite Solar Cell Fabrication With an Electrospun‐Reduced Graphene Oxide Back Electrode: A Novel Approach

AbstractIn this work, low‐cost and simple structure perovskite solar cells (PSCs) were fabricated using formamidinium lead iodide (FAPbI3) as the light absorber and reduced graphene oxide nanofibers (rGO NFs) as the counter electrode (CE). The FAPbI3 light absorber was prepared using a two‐step solution process, whereas the rGO NFs were synthesized through a simple electrospinning method. The as‐prepared FAPbI3 and rGO NFs were characterized by high‐resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and X‐ray diffraction (XRD) pattern analysis. The surface morphology of the as‐prepared FAPbI3 and rGO NFs showed crystalline and bead‐free fiber structures, as confirmed by HRTEM and FESEM image analysis. The AFM topographical images of FAPbI3 and rGO NFs further reveal the crystalline and fiber structures. XRD pattern analysis confirmed the cubic crystalline phase of FAPbI3 and the graphitic nature of rGO NFs. From the electrochemical impedance spectroscopy studies, the PSC assembled with the FAPbI3 light absorber and rGO NFs‐based CE demonstrated an electrical conductivity of 3.64 × 10−4 S cm−1. The fabricated PSC device achieved an efficiency of 8.78% compared to the 7.49% efficiency of the device with a sputtered gold CE. This work uniquely integrates advanced materials, cost‐effective manufacturing, and enhanced efficiency in PSCs using FAPbI3 light absorbers and rGO NFs, addressing key challenges in cost and sustainability in solar technology.

Harnessing SWCNT absorber based efficient CH3NH3PbI3 perovskite solar cells

This paper investigates the effect of incorporating a single-walled carbon nanotubes (SWCNTs) layer into the perovskite solar cell (PSC) structure as an effective technique to boost energy harvesting. The proposed PSC structure utilizes the SWCNTs layer underneath the CH3NH3PbI3 perovskite layer as an absorbing layer forming a novel design of (ITO/SnO2/CH3NH3PbI3/SWCNTs/NiOx/C) half tandem PSC structure. The suggested PSC structure is numerically analyzed using finite element method (FEM). The effects of varying thickness and doping concentration of the added layer and the material of rear electrode are investigated to maximize the power conversion efficiency (PCE) of the suggested PSC. Results of the 3D opto-electrical study and the energy bandgap analysis confirm that utilizing a 680 nm SWCNTs layer with doping concentration of 1.1 × 1020 cm-3 beneath a 150 nm perovskite layer enhances the PCE and short circuit current density (JSC) to 25.6%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$25.6\\%$$\\end{document} and 31.201mA/cm2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$31.201 mA/{cm}^{2}$$\\end{document}, respectively due to the improving of the PSC absorption by 27.65%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$27.65\\%$$\\end{document}. Higher performance of the proposed PSC has been achieved by using gold (Au) electrode instead of carbon (C) one, causing total enhancement of PCE and JSC of 6.185%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$6.185\\%$$\\end{document} and 9.18mA/cm2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$9.18\\;mA/cm^{2}$$\\end{document}, respectively over their values for (ITO/SnO2/CH3NH3PbI3/P3HT/NiOx/C) structure reported in previously published literature. The proposed design can be considered as an efficient alternative to the conventional PSC owing to its higher performance and reduced toxicity.

Impact of PTQ11 polymer doping on the optoelectronic and structural properties of a CH3NH3PbI3 perovskite photovoltaic cell

At present, one of the most swiftly progressing domains in solar photovoltaics is perovskite-based solar cells. Chemical modification of perovskites with foreign atoms represents a potentially fruitful approach to customizing material characteristics with the aim of enhancing the functionality and durability of solar cells. In this study, we first documented the inverted structure of PTQ11 polymer-doped perovskite solar cells composed of CH3NH3PbI3 (MAPbI3) perovskite thin film. The findings indicate that the active layer morphology is enhanced through PTQ11 doping, leading to rapid suppression of photoluminescence and delayed carrier recombination. The XRD and Raman spectral analyses revealed the crystalline, single phase, tetragonal, and highly pure MAPbI3 thin film with the preferred (220) orientation. Energy gaps ranging from 1.596 eV to 1.577 eV and absorption coefficients exceeding 105 cm−1 were characteristics of the doped thin film, which varied with the doping concentration. A transition occurred on the perovskite film’s surface to form smooth, compressed pores measuring 1.63 µm in diameter. This modification potentially enhanced the photovoltaic performance by facilitating charge transport. With an open circuit voltage of 1.11 V, a power conversion efficiency (PCE) of 18.24 %, a short-circuit current density of 22.32 mA/cm2, and a fill factor of 73.65 %, the PTQ11-9 mg/mL sample constituted the solar cell device base. Hence, the findings suggest that the doping of PTQ11 polymer represents a potentially effective approach to improve the performance of perovskite solar cells.

Exploring the theoretical potential of tungsten oxide (WOx) as a universal electron transport layer (ETL) for various perovskite solar cells through interfacial energy band alignment modulation

Perovskite solar cells (PSCs) play a pivotal role in advancing renewable energy to achieve United Nation's Sustainable Development Goal 7 (SDG 7), which aims to ensure universal access to affordable, sustainable, reliable and modern energy services. Aiming to enhance the performance of PSCs by replacing the typically used electron transport layers (ETLs: TiO2, SnO2, ZnO etc.), we theoretically investigated the viability of tungsten oxide (WOX) as a promising ETL for PSCs. Moreover, the effect of altering the energy levels of WOX on cell performance has also been analyzed through simulation. Initially, 12 (twelve) PSC structures having the combination of different perovskite (PSK: CsPbBr3, CsPbI3, FAPbBr3, FAPbI3) absorber layers with different organic hole transport layers (HTLs: Spiro-OMeTAD, P3HT, PEDOT:PSS) and a fixed ETL of WOX were optimized numerically for comparing their performance. As CsPbBr3-based PSCs showed the best performance, further simulations were performed by varying some WOX/CsPbBr3 interface properties such as interface defect density, conduction band offset (CBO) between WOX and CsPbBr3, energy bandgap (Eg) of WOX etc. Finally, the best-performed PSCs were found for the Eg = 3.5 eV of WOX and the CBO of - 0.5 eV confirming the conduction band minimum (CBM) of WOX is lower than that of CsPbBr3 by 0.5 eV. A properly chosen WOX layer enhanced the efficiency of CsPbBr3-based PSCs up to 14.65 %, 14.52 % and 16.09 %, aproaching the Shockley-Queisser (S-Q) limit (16.37% for CsPbBr3-based solar cell) from the initial values of 11.39 %, 11.27 %, and 12.49 %, respectively. This study ensures WOX is a promising ETL for which a proper PSC structure having a suitable PSK and an HTL can improve cell performance. Moreover, the importance of modifying energy levels of ETL material in enhancing the performance of PSCs is explored. As a result, this study opens a path for the researchers to develop WOX having suitable CBM and Eg, so that it can be well-suited with a properly matched PSK material resulting in enhanced cell performance.

High-Efficiency Perovskite Solar Cells with Improved Interfacial Charge Extraction by Bridging Molecules.

The interface between the perovskite layer and electron transporting layer is a critical determinate for the performance and stability of perovskite solar cells (PSCs). The heterogeneity of the interface critically affects the carrier dynamics at the buried interface. To address this, a bridging molecule, (2-aminoethyl)phosphonic acid (AEP), is introduced for the modification of SnO2/perovskite buried interface in n-i-p structure PSCs. The phosphonic acid group strongly bonds to the SnO2 surface, effectively suppressing the surface carrier traps and leakage current, and uniforming the surface potential. Meanwhile, the amino group influences the growth of perovskite film, resulting in higher crystallinity, phase purity, and fewer defects. Furthermore, the bridging molecules facilitate the charge extraction at the interface, as indicated by the femtosecond transient reflection (fs-TR) spectroscopy, leading to champion power conversion efficiency (PCE) of 26.40% (certified 25.98%) for PSCs. Additionally, the strengthened interface enables improved operational durability of ≈1400 h for the unencapsulated PSCs under ISOS-L-1I protocol.

Evaluation of AGeX3 structured perovskite solar cells based on density functional theory

Abstract Density functional theory (DFT), as a theory to explore the electron microscopic structure of materials, guides and promotes the rapid development of the perovskite field. In the context of the global energy revolution, “green”, “safe”, and “sustainable” have become the keywords in the field of perovskite research. Because of its abundant reserves on the earth, less harm to the environment and human health, strong stability, and other advantages, germanium has been widely concerned in the field of perovskite solar cells (PSCs). In this study, the differential charge densities, the total densities of states (TDOS), the partial densities of states (PDOS), and the thermodynamic properties of four AGeX3 germanium-based perovskite materials are calculated by using Materials Studio (MS). It is found that Ge atomic orbital electrons play a crucial role in the absorption of photon energy and the generation of photocurrent. The PSCs of the AGeX3 structure will perform better. This study contributes to the realization of efficient germanium-based PSCs in experiments, provides a broad prospect for researchers in this field, and plays a vital role in the future research of germanium-based perovskite.

Exploring the viability of secondary absorber materials in perovskite solar cell structures through computational analysis

Perovskite solar cells (PSCs) are at the forefront of next-generation photovoltaic technology due to their high efficiency and cost-effectiveness. To further enhance their performance, we investigate the integration of a second absorber layer alongside the conventional perovskite layer. Through extensive simulation techniques, we explore the effectiveness of silicon, Copper Indium Gallium Selenide (CIGS), and additional perovskite layers in forming a Double layered absorber perovskite solar cell (DLAPSC) structure. Our analysis of key performance metrics reveals MASnI3 as the most promising second absorber material, offering superior performance attributed to favorable band alignment and enhanced charge transport properties. In contrast, CIGS and Si layers exhibit inferior performance due to comparatively narrow bandgaps, leading to increased resistive losses. The perovskite/perovskite DLAPSC shows significant promise, achieving a notable power conversion efficiency of 41.56%. This study emphasizes the importance of meticulous parameter optimization and material selection in advancing PSC technology, highlighting the potential of DLAPSCs for renewable energy applications.

Numerical simulation of all inorganic CsPbIBr2 perovskite solar cells with diverse charge transport layers using DFT and SCAPS-1D frameworks

All inorganic CsPbX3 perovskites (X = Br and I) are excellent candidates for stable and efficient perovskite solar cells (PSCs). Among them, CsPbIBr2 demonstrated the most balanced characteristics in terms of band gap and stability. Nevertheless, the power conversion efficiency (PCE) of CsPbIBr2-based solar cells is still far from that of Hybrid PSCs, and more research is required in this aspect. Herein, DFT and SCAPS-1D frameworks are employed to explore the optimized device configurations of CsPbIBr2 PSCs. DFT is used to explore the structural and optoelectronic characteristics of CsPbIBr2, while SCAPS-1D is employed to examine various device structures of CsPbIBr2-based PSCs. The band structure demonstrated the direct band gap nature of CsPbIBr2 with a band gap of 2.12 eV. Moreover, we have used TiO2, SnO2, ZnO, WS2, IGZO, CeO2, In2S3, and CdS as ETLs, and Cu2O, CuI, MoO3, NiO, CuSCN, CuSbS2, CBTS, CFTS, and CuO as HTLs for identifying the best ETL/CsPbIBr2/HTL configurations. Among 72 device combinations, eight sets of PSCs are identified as the most efficient configurations. In addition, the influence of various parameters like the thickness of various layers, doping concentration, perovskite defect density, ETLs and interfaces, series resistances, shunt resistances, and temperature on device performance have been comprehensively studied. The results demonstrate Cu2O as the best HTL for CsPbIBr2 with each ETL, and PSC with device structure ITO/WS2/CsPbIBr2/Cu2O/C exhibited the highest PCE of 16.53%. This comprehensive investigation will provide new path for the development of highly efficient all-inorganic CsPbIBr2 solar cells.

Enhancement of inverted structure perovskite solar cell by CZTS nanoparticles

Inverted structure perovskite solar cells have attracted much attention in recent years due to their reliable operational stability, low residual, and low-temperature fabrication process. In the past few years, to accelerate their commercialization, the focus of research on the inverted structure perovskite solar cells was on the power conversion efficiency increasing. In this study nanoparticles of Cu2ZnSnS4 (CZTS) were doped into the PEDOT:PSS film as the hole transport layer (HTL) and then the interface carrier recombination quenching was observed. Consequently, it leads the s to charge carrier's collection enhancement of the Inverted perovskite solar cells. Compared to other types of HTLs, the use of CZTS HTL reduces the amount of interaction of the HTL film and the perovskite film, which results in an increment of the stability of the solar cell over time.

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.

Solvent management and Li+/Mg2+ co-doping enable efficient n-i-p NiOx-based perovskite solar cells

Spin-coating pre-fabricated NiOx nanocrystals using an annealing-free process is a compatible technique for fabricating the hole transport layer in n-i-p structured perovskite solar cells. The solvothermal method, assisted by long-chain fatty acids or amines such as oleic acid and oleylamine, has demonstrated the applicability of fabricating NiOx nanoparticles with uniform morphology and size. However, the long-chain fatty acids or amines covering the NiOx nanoparticles cannot be removed at low temperature, obstructing the transport of photo-generated holes due to their insulating characteristics. Herein, triphenylphosphine is employed to replace a portion of oleylamine in the solvothermal reaction solution. Experimental results demonstrate that the introduction of triphenylphosphine does not affect the dispersion of the synthesized NiOx nanoparticles in toluene. The as-fabricated n-i-p structured device receives an efficiency of 12.63 %. Thereafter, Li+ doping and Li+-Mg2+ co-doping strategies are used to further enhance the devices' performance. The best-behaved device with Li+-Mg2+ co-doping NiOx hole transport layer acquires an efficiency of 16.20 %. This research provides a practical approach for fabricating efficient NiOx hole transport materials for n-i-p structured perovskite solar cells.

Enhancing the Overall Performance of Perovskite Solar Cells with a Nano-Pyramid Anti-Reflective Layer

Perovskite solar cells (PSCs) still suffer from varying degrees of optical and electrical losses. To enhance the light decoupling and capture ability of Planar PSCs, an ultra-thin PSC structure with an Al2O3 pyramid anti-reflection layer (Al2O3 PARL) is proposed. The effect of the structure of the Al2O3 PARL on the photoelectric performance of PSCs was investigated by changing various parameters. Under the AM1.5 solar spectrum (300–800 nm), the average light absorption rates and quantum efficiency (QE) of PSCs containing pyramid-array textured rear layers (PARLs) were significantly higher than those of planar PSCs. The Al2O3 PARL-based PSCs achieved a light absorption rate of 96.05%. Additionally, electrical simulations were performed using the finite element method (FEM) to calculate the short-circuit current density (JSC), open-circuit voltage (VOC), and maximum power (Pmax). Based on the maximum value of the average light absorbance, the geometric structure of the Al2O3 pyramid PSCs was optimized, and the optimization results coincided with the JSC and QE results. The results of the electrical simulation indicated that the maximum JSC was 23.54 mA/cm2. Additionally, the JSC of the Al2O3 pyramid PSCs was 22.73% higher than that of planar PSCs, resulting in a photoelectric conversion efficiency (PCE) of 24.34%. As a result, the photoelectric conversion rate of the solar cells increased from 14.01% to 17.19%. These findings suggest that the presence of the Al2O3 PARL enhanced photon absorption, leading to an increase in electron–hole pairs and ultimately improving the photocurrent of the solar cells.

Study and Optimization of a New Perovskite Solar Cell Structure Based on the Two Absorber Materials Cs2TiBr6 and MASnBr3 Using SCAPS 1D

The main objective of this study is to optimize the photovoltaic parameters of a new perovskite solar cell structure (PSC) suggested, using the simulator solar cell capacitance simulator-one dimension (SCAPS-1D) which aims to improve its performance by adjusting different key variables. This new suggested cell which consists of six materials represents the major innovation point of our research, it is distinguished by a double active layer, composed of the two-cesium titanium hexabromide (Cs2TiBr6) and methylammonium tin tribromide (MASnBr3) perovskites. Using the SCAPS 1D software, the simulation allows to determine the optimal values of the various parameters to maximize the efficiency of the PSC. First, the effect of the thickness and defect densities of both Cs2TiBr6 and MASnBr3 materials on the output parameters was studied as well as the defect density in the interfaces. Subsequently, the doping density in Cs2TiBr6 and MASnBr3 was also optimized. Finally, the impact of temperature, series resistance and shunt resistance were evidenced. The results indicate that precise adjustments of these parameters can lead to significant improvements in photovoltaic performance, such as open circuit voltage of 1.105 V, short-circuit current density of 33.90 mA cm−2, fill factor of 88.01% and power conversion efficiency (PCE) 32.96%. These performances were obtained for a thickness of 700 nm for Cs2TiBr6 and 900 nm for MASnBr3, a defect density of 1014 cm−3 for each absorber layer, a defect density of 1014 cm−2 for each interface and a doping density of the order of 1018 cm−3 for each absorbent layer.

Naphthalene Diimide-Modified SnO2 Enabling Low-Temperature Processing for Efficient ITO-Free Flexible Perovskite Solar Cells.

A low-cost and indium-tin-oxide (ITO)-free electrode-based flexible perovskite solar cell (PSC) that can be fabricated by roll-to-roll processing shall be developed for successful commercialization. High processing temperatures present a challenge for the PSC fabrication on flexible substrates. The most efficient planar n-i-p PSC structures, which utilize a metal oxide as an electron transport layer (ETL), necessitate high annealing temperatures. In addition, the device performance deteriorates owing to the migration of halogen ions, which causes the oxidation of the metal electrodes. These drawbacks conflict with the development of highly efficient flexible PSCs fabricated on ITO-free transparent electrodes. Herein, an efficient ETL material that enables low-temperature processing is presented. Tin dioxide (SnO2) is modified by (sulfobetaine-N,N-dimethylamino)propyl naphthalene diimide (NDI-B) and used as an ETL. The NDI-B effectively reduces the interfacial nonradiative recombination between the ETL and perovskite and suppresses the ion migration by passivating oxygen-vacancy defects in SnO2 and strongly interacting with halogen ions, respectively. Based on the NDI-B-blended SnO2 ETL, a record PCE of 17.48% is achieved in the ITO-free flexible PSC fabricated at low temperature.

Doping PCBM with fullerene phosphinate derivatives enhances the interface energy alignment and synergistic passivation capability

Phenyl-C61-butyric acid methyl ester (PCBM) serves as a common electron transport layer (ETL) in inverted p-i-n structure perovskite solar cells (IPSCs), yet energy barriers and insufficient passivation at the PCBM-perovskite interface hinder device effectiveness and durability. In this study, we present a series of novel Fullerene Phenylacid Ester Derivatives (FPEDs: FPP, FTPP, FDPP) incorporated into PCBM. Our investigations illustrate that FPEDs effectively act to passivate the perovskite surface by forming robust interactions with uncoordinated Pb2+ ions via the phosphine oxide groups present in their molecular structures, thereby enhancing the stability of the devices. Moreover, these additives elevate the energy level of the lowest unoccupied molecular orbital (LUMO) of ETL, diminish the electron injection barrier, and enhance the efficiency of interlayer electron transport. Incorporating FPEDs enhances ETL coverage on the perovskite layer, reducing leakage current significantly. Notably, Devices with PCBM/FTPP achieved a peak PCE of 23.62% and showed superior stability, maintaining 96.8% of the initial PCE after 500 h, while control devices retained merely 80.7% over the same period.

Performance optimization of lead-free potassium germanium halide based perovskite solar cells: A numerical study

Conventional lead-halide perovskite solar cells (PSCs) have great potential as top contenders for commercial utilization due to their impressive performance. Nevertheless, the stability issues and undue toxicity have limited their widespread use. Consequently, lead-free germanium-based PSCs have materialized as potential substitutes due to their high working efficiency and exceptional sustainability. The current study has examined various configurations of non-toxic inorganic potassium germanium trichloride (KGeCl3) based PSC structure by using different Hole Transport Layers (HTL) and Electron Transport Layers (ETLs) respectively. This work proposes an efficient Ge-based PSC (structure; FTO/MoO3/KGeCl3/WS2/Au), which has been optimized theoretically using SCAPS-1D. The influence of the material parameters, such as the thickness of the absorber layer (nm), donor density (Nd), acceptor density (Na), absorber defect density(Nt), interface layer defect density (IL1& IL2), series resistance (Rs) and shunt resistance (Rsh), and working temperature (K), has been optimized. The open circuit voltage (Voc), current density (Jsc), fill factor (FF), and power conversion efficiency (PCE) of KGeCl3-based PSC have all been commendably optimized. The results indicated WS2 as the most effective ETL for KGeCl3 with MoO3 as an HTL, yielding notable cell performance with Voc of 0.88 V, Jsc of 41.45 mA/cm2, FF of 81.76 %, and PCE of 29.83 %. The outcomes of this simulation study suggest the utilization of KGeCl3 as the absorber layer, in conjunction with WS2 and MoO3 as advanced ETL and HTL layers, which pays the way for continued development and optimization of Ge-based PSCs for potential applications.

Advanced Optoelectronic Modeling and Optimization of HTL-Free FASnI3/C60 Perovskite Solar Cell Architecture for Superior Performance.

In this study, a novel perovskite solar cell (PSC) architecture is presented that utilizes an HTL-free configuration with formamide tin iodide (FASnI3) as the active layer and fullerene (C60) as the electron transport layer (ETL), which represents a pioneering approach within the field. The elimination of hole transport layers (HTLs) reduces complexity and cost in PSC heterojunction structures, resulting in a simplified and more cost-effective PSC structure. In this context, an HTL-free tin HC(NH2)2SnI3-based PSC was simulated using the solar cell capacitance simulator (SCAPS) within a one-dimensional framework. Through this approach, the device performance of this novel HTL-free FASnI3-based PSC structure was engineered and evaluated. Key performance parameters, including the open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), power conversion efficiency (PCE), I-V characteristics, and quantum efficiency (QE), were systematically assessed through the modulation of physical parameters across various layers of the device. A preliminary analysis indicated that the HTL-free configuration exhibited improved I-V characteristics, with a PCE increase of 1.93% over the HTL configuration due to improved electron and hole extraction characteristics, reduced current leakage at the back contact, and reduced trap-induced interfacial recombination. An additional boost to the device's key performance parameters has been achieved through the further optimization of several physical parameters, such as active layer thickness, bulk and interface defects, ETL thickness, carrier concentration, and back-contact materials. For instance, increasing the thickness of the active layer PSC up to 1500 nm revealed enhanced PV performance parameters; however, further increases in thickness have resulted in performance saturation due to an increased rate of hole-electron recombination. Moreover, a comprehensive correlation study has been conducted to determine the optimum thickness and donor doping level for the C60-ETL layer in the range of 10-200 nm and 1012-1019 cm-3, respectively. Optimum device performance was observed at an ETL-C60 ultra-thin thickness of 10 nm and a carrier concentration of 1019 cm-3. To maintain improved PCEs, bulk and interface defects must be less than 1016 cm-3 and 1015 cm-3, respectively. Additional device performance improvement was achieved with a back-contact work function of 5 eV. The optimized HTL-free FASnI3 structure demonstrated exceptional photovoltaic performance with a PCE of 19.63%, Voc of 0.87 V, Jsc of 27.86 mA/cm2, and FF of 81%. These findings highlight the potential for highly efficient photovoltaic (PV) technology solutions based on lead-free perovskite solar cell (PSC) structures that contribute to environmental remediation and cost-effectiveness.

Strong-bonding hole-transport layers reduce ultraviolet degradation of perovskite solar cells

The light-emitting diodes (LEDs) used in indoor testing of perovskite solar cells do not expose them to the levels of ultraviolet (UV) radiation that they would receive in actual outdoor use. We report degradation mechanisms of p-i-n–structured perovskite solar cells under unfiltered sunlight and with LEDs. Weak chemical bonding between perovskites and polymer hole-transporting materials (HTMs) and transparent conducting oxides (TCOs) dominate the accelerated A-site cation migration, rather than direct degradation of HTMs. An aromatic phosphonic acid, [2-(9-ethyl-9H-carbazol-3-yl)ethyl]phosphonic acid (EtCz3EPA), enhanced bonding at the perovskite/HTM/TCO region with a phosphonic acid group bonded to TCOs and a nitrogen group interacting with lead in perovskites. A hybrid HTM of EtCz3EPA with strong hole-extraction polymers retained high efficiency and improved the UV stability of perovskite devices, and a champion perovskite minimodule—independently measured by the Perovskite PV Accelerator for Commercializing Technologies (PACT) center—retained operational efficiency of >16% after 29 weeks of outdoor testing.

Enhanced efficiency of bifacial perovskite solar cells using computational study

The most rapidly expanding type of solar cells are the Perovskite Solar Cells (PSCs), because of its high device performance, ease of synthesis, high open-circuit voltage, and affordability. Despite these advantages, the development of perovskite-based solar cells continues to be impeded by the issues with perovskite stability and the utilization of the hazardous heavy element lead (Pb). The study emphasizes on the bifacial structure that maintains the conventional absorber layer and electron transport layer (ETL) in the optimized PSC structure. This study employs SCAPS software for device simulation to comprehensively analyze how various parameters affect the performance of solar cells. Additionally, doping concentration variation in both ETL and HTL are explored. The simulation reveals that changing device structure from monofacial to bifacial significantly influences PSC performance, demonstrating that optimizing individual layers effectively enhances overall solar cell performance. The optimized structure achieves impressive PSC performance metrics through parametric analysis, such as voltage (VOC) of 1.18 V, fill factor (FF) of 82.24%, current density (JSC) of 27.12 mA/cm2, power conversion efficiency (PCE) of 27.90% for an incident solar spectrum from the ETL side, and power conversion efficiency (PCE) of 19.86% for an incident solar spectrum from the HTL side, the calculated bifaciality factor (BF) for this structure is 71.18%.

Highly transparent and conductive Ga-doped InWO multi-component electrodes for Perovskite photovoltaics

Wide-bandgap Ga-doped InWO (GIWO) transparent conductive electrodes (TCE) were fabricated by co-sputtering IWO and Ga2O3, followed by rapid thermal annealing (RTA), with the effects of the Ga dopant content on the electrical, optical, structural, and morphological properties of the GIWO multi-component electrodes investigated to optimize the GIWO electrode. According to the figure of merit (FOM), the GIWO film with a Ga content of 2.1 at% exhibited a low sheet resistance of 9.9 Ohm/square and high transmittance of 91.71 % at a wavelength of 550 nm. The presence of a high Lewis acid strength (LAS) dopant of Ga (1.16) and W (3.15) led to an increase in the carrier mobility of GIWO and transmittance in the near infrared wavelength region. In addition, the strongly preferred (222) and (400) orientations of the GIWO grains increase the carrier mobility and improve the surface morphology of the GIWO electrodes. The successful operation and superior performance of the planar p-i-n structured perovskite solar cells (PSC) fabricated on GIWO electrodes indicate the feasibility of GIWO as a substitute for conventional Sn-doped In2O3 electrodes. The highest-performing PSC with GIWO electrodes exhibited reliable hysteresis with an efficiency difference of less than 1 % depending on the scan direction under standard AM1.5 G conditions.