Researchers at several India-based institutes have explained that single junction perovskite solar cells (PSCs) face efficiency limitations mainly due to bandgap constraints of available perovskite materials, leading to the ineffective utilization of full solar spectrum. Though the perovskite materials such as MAGeI3 and Cs2AgBiBr6 have been found to be efficient absorber materials thanks to their stable and non-toxic nature, the PSCs fabricated with these materials as light absorbers have not shown the power conversion efficiency (PCE) suitable for commercial applications.
To address this issue, the team studied the performance of single junction PSCs with MAGeI3 and Cs2AgBiBr6 as photon absorbers, using optimization methods employing SCAPS 1D tool. The study also investigated the optimization of the tandem device composed of a dual absorber PSC designed by stacking the perovskite materials, MAGeI3 and Cs2AgBiBr6 for top cell with CIGS for bottom cell to push the boundaries of the device PCE.
The single junction PSCs designed with MAGeI3 and Cs2AgBiBr6 as absorber layers separately have attained a PCE of 11.6 % and 7.36 % respectively.
When the device was modelled by stacking the absorber layers MAGeI3 and Cs2AgBiBr6 to form a dual absorber PSC, a PCE of 17.75 % is achieved, with optimized input parameters for the absorber materials.
In the subsequent stage of modelling, the dual absorber PSC with the optimized PCE of 17.75 % was used as the top sub cell along with a CIGS bottom sub cell exhibiting an optimized PCE of 21.64 %. The optimized 4-T tandem device provided a PCE of 39.39 % whereas the 2-T monolithic tandem architecture with the same materials exhibited a PCE of 23.20 %.
The significant improvement in PCE shows the potential of such tandem configurations to surpass the drawbacks of single junction PSCs and opens the path for future research studies on multi-absorber PSC tandem device architecture for enhanced efficiency.
