Enhancement of Stability of Inverted Flexible Perovskite Solar Cells by Employing Graphene-Quantum-Dots Hole Transport Layer and Graphene Transparent Electrode Codoped with Gold Nanoparticles and Bis(trifluoromethanesulfonyl)amide

We first report p-i-n-type perovskite solar cells (PSCs) using graphene quantum dots (GQDs) hole transport layer (HTL) and graphene transparent conductive electrode codoped with gold nanoparticles and bis(trifluoromethanesulfonyl)amide. The PSCs on rigid glass substrates show maximum power conversion efficiency (PCE) of 17.02/17.15% for forward/reverse scans, comparable to those (17.53/17.55%) of the control cells with poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) HTL. As 30 d elapsed in N2 atmosphere, only 28% of the PCE degradation is observed for the GQDs HTL, while the PCE is reduced by 42% for the PEDOT:PSS HTL. Flexible PSCs with GQDs HTL exhibit 13/15% PCE for forward/reverse scans, respectively, and maintain 70% of the original PCE value even after 3000 bending cycles at a curvature radius of 4 mm.