Controllable electrolysis doping of organic semiconductors for stable perovskite solar cells

The conventional doping method of organic semiconductors (commonly including lithium bis(trifluoromethane)sulfonimide [LiTFSI]) served as hole transport layers in perovskite solar cells (PSCs) suffers from a complex, time-consuming oxidation process, detrimentally impacting device stability. Herein, we propose a novel electrolysis doping strategy to modulate organic semiconductors, enabling controllable doping and effective Li⁺ removal. This electrolysis doping exploits holes with tunable oxidizing capabilities to oxidize organic semiconductors into ion radicals at the surface of the anode electrode, which exhibits a high reproducibility and a universal application on different organic semiconductors. Simultaneously, Li⁺ ions can be reduced to Li atoms at the surface of the cathode electrode, thus removing stability-damaging residual Li⁺. Accordingly, the regular PSCs using electrolyzed 2,2',7,7'-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro) achieve a power conversion efficiency (PCE) of 26.16%, and the inverted-structured PSCs using electrolyzed poly[bis(4-phenyl) (2,4,6-trimethylphenyl)amine (PTAA) achieve a PCE of 25.57% with satisfying stability by maintaining 91% of initial efficiency after operating for 1,400 h under continuous one-sun illumination.