Thickness-derived optical-electrical management in Sn-based perovskite solar cells

Abstract

Tin-based perovskite solar cells (TPSCs) have attracted great attention due to their promising photovoltaic performance and environmental friendliness. Adequate photon trapping and efficient carrier utilization are known to be the keys to achieving high-performance devices, which are closely related to the thickness of the light-absorbing layer and the quality of film formation, respectively. Due to the ultra-fast crystallization characteristics and low defect formation energy, thick tin-based perovskite films are faced with poor electrical performance due to poor quality. Thin tin-based perovskite films are easy to achieve low defects and high crystallization quality, but insufficient thickness leads to the problem of insufficient light trapping. To address these issues, we have thoroughly investigated the various aspects of the photoelectric conversion process in TPSC devices and, for the first time, explored the behavior of front-end optical field management. It is found that the self-constructed microcavity effect can effectively improve the light trapping efficiency under the premise that a thin light-absorbing layer is used, so that sufficient photon trapping and excellent carrier transport characteristics can be ensured simultaneously to realize a high-performance device. Different from the traditional film formation and defect modulation strategy, the present work provides a feasible idea for the performance enhancement of TPSC devices, and is also of great significance for cost control and environmental protection issues in commercial applications.