Design and optimization of an economic HTL-free, non-toxic double-layer perovskite solar cell for enhanced performance and stability

Abstract Carbon-based perovskite solar cells present an attractive option for large-scale production due to their notable stability and cost-effectiveness. Streamlining the architecture of perovskite solar cells and eliminating the hole transport layer contribute to additional cost savings. Hole transport layer free perovskite solar cells are more efficient to fabricate than regular perovskite solar cells making them a strong candidate for advancing large-scale production processes. Despite the enhanced stability of double perovskite solar cells, their efficiency remains lower than that of single perovskite cells. In response to environmental concerns, efforts are underway to develop lead-free perovskite absorber layers, with Cs 2 AgBiBr 6 identified as a promising candidate. In experimental studies, Cs 2 AgBiBr 6 double perovskite solar cell had achieved a low band-gap ( E g = 1.64 eV) through hydrogenation treatment, it shows potential for further research and development. To enhance the performance of this double perovskite solar cell, we have excluded the hole transport layer and opted for carbon as a back electrode. Utilizing SCAPS-1D simulation software, we conducted optimizations, including selecting an appropriate transparent conducting oxide and electron transport layer, adjusting the absorber layer thickness, optimizing acceptor density, modulating the doping density and defect density in the absorber layer, and optimizing the work function of the front electrode. These optimizations resulted in improved efficacy, with the fluorine doped tin oxide/tungsten oxide Cs 2 AgBiBr 6 /Carbon configuration demonstrating exceptional photovoltaic performance, featuring open-circuit voltage = 1.41 V, short-circuit current density = 21.95 mA cm −2 , power conversion efficiency = 25.28 %, and fill factor = 81.54 %.