Boosting efficiency of eco-friendly perovskite solar cell through optimization of novel charge transport layers

Mixed cations tin-germanium perovskite: A promising approach for enhanced solar cell applications

Significant progress has been made over the years to improve the stability and efficiency of rapidly evolving tin-based perovskite solar cells (PSCs). One powerful approach to enhance the performance of these PSCs is through compositional engineering techniques, specifically by incorporating a mixed cation system at the A-site and B-site structure of the tin perovskite. These approaches will pave the way for unlocking the full potential of tin-based PSCs. Therefore, in this study, a theoretical investigation of mixed A-cations (FA, MA, EA, Cs) with a tin-germanium-based PSC was presented. The crystal structure distortion and optoelectronic properties were estimated. SCAPS 1-D simulations were employed to predict the photovoltaic performance of the optimized tin-germanium material using different electron transport layers (ETLs), hole transport layers (HTLs), active layer thicknesses, and cell temperatures. Our findings reveal that EA0.5Cs0.5Sn0.5Ge0.5I3 has a nearly cubic structure (t = 0.99) and a theoretical bandgap within the maximum Shockley-Queisser limit (1.34 eV). The overall cell performance is also improved by optimizing the perovskite layer thickness to 1200 nm, and it exhibits remarkable stability as the temperature increases. The short-circuit current density (Jsc) remains consistent around 33.7 mA/cm2, and the open-circuit voltage (Voc) is well-maintained above 1 V by utilizing FTO as the conductive layer, ZnO as the ETL, Cu2O as the HTL, and Au as the metal back contact. This configuration also achieves a high fill factor ranging from 87 % to 88 %, with the highest power conversion efficiency (PCE) of 31.49 % at 293 K. This research contributes to the advancement of tin-germanium perovskite materials for a wide range of optoelectronic applications.

Interface engineering and defect passivation for enhanced hole extraction, ion migration, and optimal charge dynamics in both lead-based and lead-free perovskite solar cells

The study elucidates the potential benefits of incorporating a BiI3 interfacial layer into perovskite solar cells (PSCs). Using MAPbI3 and MAGeI3 as active layers, complemented by the robust TiO2 and Spiro-OMeTAD as the charge-transport-layers, we employed the SCAPS-1D simulation tool for our investigations. Remarkably, the introduction of the BiI3 layer at the perovskite-HTL interface significantly enhanced hole extraction and effectively passivated defects. This approach minimized charge recombination and ion migration towards opposite electrodes, thus elevating device performance relative to conventional configurations. The efficiency witnessed a rise from 19.28 to 20.30% for MAPbI3 and from 11.90 to 15.57% for MAGeI3. Additionally, MAGeI3 based PSCs saw an improved fill-factor from 50.36 to 62.85%, and a better Jsc from 13.22 to 14.2 mA/cm2, signifying reduced recombination and improved charge extraction. The FF for MAPbI3 based PSCs saw a minor decline, while the Voc slightly ascended from 1.24 to 1.25 V and Jsc from 20.01 to 21.6 mA/cm2. A thorough evaluation of layer thickness, doping, and temperature further highlighted the critical role of the BiI3 layer for both perovskite variants. Our examination of bandgap alignments in devices with the BiI3 interfacial layer also offers valuable understanding into the mechanisms fueling the observed improvements.

A comprehensive review on the advancements and challenges in perovskite solar cell technology

Perovskite solar cells (PSCs) have emerged as revolutionary technology in the field of photovoltaics, offering a promising avenue for efficient and cost-effective solar energy conversion. This review provides a comprehensive overview of the progress and developments in PSCs, beginning with an introduction to their fundamental properties and significance. Herein, we discuss the various types of PSCs, including lead-based, tin-based, mixed Sn-Pb, germanium-based, and polymer-based PSCs, highlighting their unique attributes and performance metrics. Special emphasis is given to halide double PSCs and their potential in enhancing the stability of PSCs. Charge transport layers and their significance in influencing the overall efficiency of solar cells are discussed in detail. The review also explores the role of tandem solar cells as a solution to overcome the limitations of single-junction solar cells, offering an integrated approach to harness a broader spectrum of sunlight. This review concludes with challenges associated with PSCs and perspective on the future potential of PSCs, emphasizing their role in shaping a sustainable energy landscape. Through this review readers will gain a comprehensive insight into the current state-of-the-art in PSC technology and the avenues for future research and development.

Evaluating the influence of novel charge transport materials on the photovoltaic properties of MASnI3 solar cells through SCAPS-1D modelling

In recent decades, substantial advancements have been made in photovoltaic technologies, leading to impressive power conversion efficiencies (PCE) exceeding 25% in perovskite solar cells (PSCs). Tin-based perovskite materials, characterized by their low band gap (1.3 eV), exceptional optical absorption and high carrier mobility, have emerged as promising absorber layers in PSCs. Achieving high performance and stability in PSCs critically depends on the careful selection of suitable charge transport layers (CTLs). This research investigates the effects of five copper-based hole transport materials and two carbon-based electron transport materials in combination with methyl ammonium tin iodide (MASnI3) through numerical modelling in SCAPS-1D. The carbon-based CTLs exhibit excellent thermal conductivity and mechanical strength, while the copper-based CTLs demonstrate high electrical conductivity. The study comprehensively analyses the influence of these CTLs on PSC performance, including band alignment, quantum efficiency, thickness, doping concentration, defects and thermal stability. Furthermore, a comparative analysis is conducted on PSC structures employing both p-i-n and n-i-p configurations. The highest-performing PSCs are observed in the inverted structures of CuSCN/MASnI3/C60 and CuAlO2/MASnI3/C60, achieving PCE of 23.48% and 25.18%, respectively. Notably, the planar structures of Cu2O/MASnI3/C60 and CuSbS2/MASnI3/C60 also exhibit substantial PCE, reaching 20.67% and 20.70%, respectively.

Comprehensive analysis of heterojunction compatibility of various perovskite solar cells with promising charge transport materials

The allure of perovskite solar cells (PSCs), which has captivated the interest of researchers, lies in their versatility to incorporate a wide range of materials within the cell's structure. The compatibility of these materials plays a vital role in the performance enhancement of the PSC. In this study, multiple perovskite materials including FAPbI3, MAGeI3 and MASnI3 are numerically modelled along with the recently emerged kesterite (CBTS, CMTS, and CZTS) and zinc-based (ZnO and CdZnS) charge transport materials. To fully explore the potential of PSCs and comprehend the interplay among these materials, a total of 18 PSC structures are modeled from different material combinations. The impact of band gap, electron affinity, absorption, band alignment, band offset, electric field, recombination rate, thickness, defects, and work function were analyzed in detail through a systematic approach. The reasons for varying performance of different PSCs are also identified. Based on the simulated results, the most suitable charge transport materials are CdZnS/CMTS for FAPbI3 producing a power conversion efficiency (PCE) of 22.05%, ZnO/CZTS for MAGeI3 with PCE of 17.28% and ZnO/CBTS for MASnI3 with a PCE of 24.17%.

Optimization and Efficiency Enhancement of Modified Polymer Solar Cells

In this study, an organic bulk heterojunction (BHJ) solar cell with a spiro OMeTAD as a hole transport layer (HTL) and a PDINO as an electron transport layer (ETL) was simulated through the one-dimensional solar capacitance simulator (SCAPS-1D) software to examine the performance of this type of organic polymer thin-film solar cell. As an active layer, a blend of polymer donor PBDB-T and non-fullerene acceptor ITIC-OE was used. Numerical simulation was performed by varying the thickness of the HTL and the active layer. Firstly, the HTL layer thickness was optimized to 50 nm; after that, the active-layer thickness was varied up to 80 nm. The results of these simulations demonstrated that the HTL thickness has rather little impact on efficiency while the active-layer thickness improves efficiency significantly. The temperature effect on the performance of the solar cells was considered by simulations performed for temperatures from 300 to 400 K; the efficiency of the solar cell decreased with increasing temperature. Generally, polymer films are usually full of traps and defects; the density of the defect (Nt) value was also introduced to the simulation, and it was confirmed that with the increase in defect density (Nt), the efficiency of the solar cell decreases. After thickness, temperature and defect density optimization, a reflective coating was also applied to the cell. It turned out that by introducing the reflective coating to the back side of the solar cell, the efficiency increased by 2.5%. Additionally, the positive effects of HTL and ETL doping on the efficiency of this type of solar cells were demonstrated.