Efficiency boost of perovskite solar cell in homojunction configuration through tailored band alignment and p-n doping profile

The relentless quest for sustainable and eco-friendly energy sources can be addressed through solar cells which convert solar energy to electrical energy. In the family of solar cells, perovskite solar cells (PSCs) have seen an astonishing growth in power conversion efficiency (PCE) to which homojunction perovskite is the newest addition. Although numerous studies have examined PCE enhancement through energy band-offset optimization in the intrinsic PSCs, to date, such a study has never been reported in a homojunction configuration. Considering the enormous potential of homojunction PSCs and the importance of band offset, here we numerically identified the optimized range of conduction and valance band offset (CBO and VBO) in conjunction with donor and acceptor density inside the perovskite layer to boost their photovoltaic efficiency. The effect of the CBO and donor density is found to be superior to the VBO and acceptor density. Unlike intrinsic PSCs, the cliff in the energy band diagram drastically reduces the PCE for the CBO. The optimum CBO and donor density are around 0 to +0.1 eV and 2 × 1017 cm−3 respectively. The PCE is higher and nearly constant for a VBO > 0 eV and acceptor density > 7 × 1017 cm−3. With the optimum values of doping density and band offsets, the maximum PCE is calculated to be 25.43% in the presence of all possible losses and an optimum perovskite thickness of 600 nm with a 30:70% ratio of n and p-doped segments.