Work

Optimized solar conversion achieved with double halide X2NaIrCl6 (X = Rb, Cs) perovskites for optoelectronic and photovoltaic applications

Year: 2025

Type: article

Abstract: Considering the environmental concerns of lead Hazardousness and durability concerns in lead-based perovskite solar cells (PSCs), lead-free alternatives like X 2 NaIrCl 6 (X = Rb, Cs) have gained significant attention. This investigation carries out an analysis of the structural and optoelectronic behaviour of X 2 NaIrCl 6 (X = Rb, Cs) using DFT to assess its potential for absorber material for solar cells (SCs). Structural stability of X 2 NaIrCl 6 ( X = Rb, Cs) double perovskites was analysed using tolerance factors ( τ 1 , μ , τ 2 ), with dynamical stability ensured through phonon dispersion. Negative and binding energy ( E b ) and formation energy ( E f ) further validated their stability. Direct band gaps, determined utilizing the TB-mBJ (GGA-PBE) approach, the values were determined to be 2.02 eV (0.97 eV) for Rb 2 NaIrCl 6 and 1.93 eV (0.92 eV) for Cs 2 NaIrCl 6 , placing them in the recommended range (0.8- 2.2 eV) for photoelectric conversion. X 2 NaIrCl 6 (X = Rb, Cs) double perovskites exhibit remarkable potential for photovoltaic applications, driven by their high absorption coefficients (∼10 4 ) and favourable optical properties, including low energy loss and minimal reflectivity (<15 %). These attributes highlight their promise for high efficiency and low-cost materials for advanced optoelectronic and solar energy devices. SCAPS-1D software employed to identify the most efficient solar cell designs by incorporating various HTLs and ETLs. Among 40 tested configurations, the ITO/ZnO/Cs 2 NaIrCl 6 /Cu 2 O structure attains the maximum PCE of ∼20.39 %, while ITO/ZnO/Rb 2 NaIrCl 6 /Cu 2 O achieves ∼19.16 %. Additionally, the study examines the effects of varying ETL/absorber thicknesses and series and shunt resistances, and temperature on photovoltaic performance. A detailed investigation was conducted on the principal photovoltaic indicators, such as current-voltage characteristics, capacitance, quantum efficiency, Mott Schottky parameters, and the processes governing photocarrier generation and recombination. These findings highlight X 2 NaIrCl 6 (X = Rb, Cs) as a suitable material for high-performance optoelectronic and photovoltaic real-world applications.

Source: Energy Nexus

DOI: 10.1016/j.nexus.2025.100549