Enhanced efficiency and stability of inverted perovskite solar cells by carbon dots cathode interlayer via solution process

Abstract

Abstract Interfacial engineering has been widely recognized as among the most effective approaches to deriving high performance perovskite solar cells (PSCs). [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) and silver (Ag) were extensively used as the electron transport material and cathode material in the inverted device. However, the energy level mismatch between PC61BM and Ag cathode has a possibility to severely affect the electron extraction and transportation. Hereby, only alcohol-soluble carbon dots (CDs) were synthesized and applied as a cathode interlayer (CIL) through a simple solution-process to make alteration to the interface between PC61BM and Ag in inverted PSCs, the PC61BM/CDs layer was generated with low trap-state density, high electrical conductivity, high electron mobility and appropriate energy level. Finally, the inverted device with the CDs CIL exhibited a power conversion efficiency (PCE) of 17.34% with the steady-state output PCE reaching 16.96%. The stability of devices was also enhanced due to the hydrophobicity of the CDs cathode interlayer. The efficiency of inverted PSCs with PC61BM/CDs layer remained 70% of the initial PCE under dry condition after 40 days versus only 20% of the initial PCE for the PCBM ETL without CDs.