Umpolung-EDTA Enabled Monolithic Inorganic Perovskite/Silicon Tandem Solar Cells with an Efficiency of 27.92%

Abstract

Inverted inorganic perovskite solar cells (IPSCs) are excellent top cell candidates for tandem solar cells (TSCs). However, unsatisfactory P/I interface properties limit the further improvement of efficiency. Here, a chemically modified ethylenediamine acetic acid (EDTA) strategy was developed to improve the P/I interface properties and holes extraction. The polarity conversion from n-type EDTA to weak p-type EDTA-N was realized, and gradient energy level alignment was formed between NiOx and CsPbI3 after EDTA-N introduced. As a result, a record power conversion efficiency (PCE) of 20.71% was achieved for inverted CsPbI3 IPSCs prepared in ambient air. Moreover, p-i-n type monolithic inorganic perovskite/silicon tandem solar cells (IPTSCs) were prepared and achieved a champion PCE of 27.92% (certified 27.18%). Additionally, the unencapsulated IPTSCs exhibited remarkable thermal stability and long-term operation photostability.

Keywords: Inverted inorganic perovskite solar cells, Inorganic perovskite/silicon tandem solar cells, Defects passivation, Energy alignment.