Copper iodide-PEDOT:PSS double hole transport layers for improved efficiency and stability in perovskite solar cells

The hole transport layer (HTL) plays an important role in perovskite solar cells (PSCs). We demonstrate the cupper iodide (CuI)/poly (3,4-ethylenedioxythiophene) poly (styrenesulphonate) (PEDOT:PSS) double layers as the anode buffer layer for efficient hole transport in PSCs. An obvious enhancement of open-circuit voltage and power conversion efficiency (PCE) is observed, and a final PCE of 14.3% is achieved. While the single PEDOT:PSS based device’s PCE is 12.9%. The inorganic CuI buffer layer significantly enhanced the hole extraction from the perovskite film, as revealed from the photoluminescence spectra. The average exciton lifetime is reduced to 2.7 ns. Moreover, the devices with double HTLs structure exhibit better long time stability. The PCE remains 88% of the initial value after 720 h’ storage.