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

Mathematical Modeling and Optimization of Highly Efficient Nontoxic All-Inorganic CsSnGeI3-Based Perovskite Solar Cells with Oxide and Kesterite Charge Transport Layers

Despite exceptional optoelectronic properties and rapidly increasing efficiency of perovskite solar cells (PSCs), the issues of toxicity and device instability have hampered the commercialization of this renewable energy technology. Lead (Pb) being the main culprit creates major environmental risks and therefore must be replaced with a nontoxic material such as tin (Sn), germanium (Ge), etc. Moreover, replacing organic cations in the perovskite's ABX3 structure with inorganic ones like cesium (Cs) helps aid the stability issues. This study uses six different kesterite-based hole transport layers (HTLs) and three different metal oxide-based electron transport layers (ETLs) to numerically simulate and optimize all-inorganic CsSnGeI3 PSCs. Metal oxide ETLs are used in this study due to their large band gap, while kesterite HTLs are used due to their excellent conductive properties. All of the simulations are performed under standard testing conditions. A total of 18 novel planar (n-i-p) PSCs are modeled by the combination of various charge transport layers (CTLs), and the device optimization was done to enhance the power conversion efficiencies (PCEs) of the PSCs. Furthermore, the effect of CTLs on the energy band alignment, electric field, quantum efficiency, light absorption, and recombination rate is analyzed. Additionally, a detailed analysis of the impact of defect density (Nt), interface defects (ETL/Perv, Perv/HTL), temperature, and work function on the functionality of 18 different CsSnGeI3-based PSCs is conducted. The simulation findings demonstrate that SnO2/CsSnGeI3/CNTS is the most efficient optimized PSC among all of the simulated structures, with a PCE of 27.33%, Jsc of 28.04 mA/cm2, FF of 85%, and Voc of 1.14 V.

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.

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.