Unlocking the full potential of monolithic perovskite/biPoly™ Si tandem devices through in-depth analysis and detailed engineering

Abstract

Perovskite/Si tandem solar cells have emerged as one highly promising tandem configuration of tandem devices for 1-Sun photovoltaic systems. Up to now, heterojunction (HJ) cells have been the dominant silicon bottom cell structure and holds the record efficiency of dual-junction perovskite/Si tandem cells, whereas the investigation on perovskite/Si tandem cells using Si bottom cells that dominate today's mass markets (such as PERC and TOPCon) is still limited. In this work, we delve into the crucial optical and electrical engineering aspects required for perovskite/Si devices based on bifacial TOPCon structures (biPoly™), which has high efficiency potential as a single-junction Si cell, enables TCO-free contacts and is expected to be compatible with current mass production technologies. Simulations predict that such devices can potentially achieve a current density of 20.4 mA/cm2 despite of the parasitic absorption in poly-Si layers, comparable to that of HJ-based perovskite-Si tandem devices. We also demonstrate through simulations that edge and peripheral recombination effects can be mitigated by selecting an appropriate substrate size and employing locally doped poly-Si layers. Such improvements are also preliminarily verified with a prototype device. By carefully designing device structures and advancing fabrication techniques, perovskite/biPoly™ Si tandem cells can come closer to realizing the full potential of biPoly™ cells and achieve efficiencies comparable to those observed in devices utilizing HJ cells.