Indium-doped ZnO mesoporous nanofibers as efficient electron transporting materials for perovskite solar cells

We introduce a viable electrospinning route for the development of highly porous indium-doped (In-doped) ZnO nanofibers as electron transporting materials (ETMs) in perovskite solar cells (PSCs) for the first time ever. The nanofibers ETMs with optimal thickness leads to highly efficient and hysteresis-free PSCs with an average power conversion efficiency (PCEavg) of 16.03% and a best power conversion efficiency (PCEbest) of 17.18%, thanks to high porosity and high crystallinity of the nanofibers, better infiltration of the absorber and rapid charge transport characteristics due to indium (In) doping. Furthermore, the modification of In-doped ZnO nanofibers ETMs, by coating a thin layer of a polymer polyethyleneimine (PEI) further enhances the PCEavg to 16.86% (PCEbest = 18.69%) by effectively reducing the energy barrier for electron extraction due to a reduced work function. This study reveals that In-doped ZnO nanofibers are the best ETMs for generating the inexpensive and high efficiency PSCs with long-term stability.