Polyelectrolyte based hole-transporting materials for high performance solution processed planar perovskite solar cells

Using polyelectrolytes (P3CT-Na) as hole-transporting materials (HTMs), high performance inverted perovskite solar cells with a PCE of 16.6% could be obtained, which was more than 20% improvement compared with those based on the PEDOT:PSS HTM (PCE of 13.7%). The performance improvement can be ascribed to the desirable match of energy levels as well as the better crystalline properties and larger grain size of CH₃NH₃PbCl_3-xI_x films on P3CT-Na. Importantly, rather good performance with PCE over 11% is achievable even if the P3CT-Na thickness ranges from 1 nm to 52 nm. Our work indicated the promising applications of polyelectrolyte based HTMs in perovskite solar cells and may provide some insights into the design and synthesis of new HTMs to further improve the device performance.