Enhanced Interface Properties for Efficient Monolithic Inorganic Perovskite/Silicon Tandem Solar Cell

Abstract Inorganic perovskites are excellent top cell candidates for silicon‐based tandem solar cells (TSCs) due to good thermal stability and suppressed phase segregation under illumination. However, unsatisfactory hole extraction and nonradiative recombination lead to significant voltage and fill factor losses. Here, a weak p‐type material of ethylenediamine acetic acid methylamine (EDTA‐N) combined with nickel oxide (NiO _x ) is developed as a hole selective layer. The EDTA‐N as a bridge between CsPbI ₃ and NiO _x , effectively enhances carrier extraction from CsPbI ₃ to NiO _x and also facilitates the subsequent growth of high‐quality inorganic perovskite films. Furthermore, the EDTA‐N can coordinate with uncoordinated Pb ²⁺ at the bottom interface while suppressing interfacial non‐radiative recombination. Moreover, the formation of gradient energy level alignment between CsPbI ₃ and NiO _x results in higher open‐circuit voltage. The resulting CsPbI ₃ inorganic perovskite solar cells achieves a power conversion efficiency (PCE) of 21.52%. A record PCE of 27.92% (certified 27.18%) of inorganic perovskite/silicon TSCs (IPTSCs) is also achieved. In air, without encapsulation, the IPTSCs maintained 96.89% of its initial efficiency after 500 h of continuous illumination and retained 87.48% of its initial efficiency after 1000 h of heating at 85 °C in a nitrogen atmosphere.