Cesium-doped methylammonium lead iodide perovskite light absorber for hybrid solar cells

We demonstrate cesium-doping in methylammonium lead iodide perovskites (CsxMA1−xPbI3) light absorbers to improve the performance of inverted-type perovskite/fullerene planar heterojunction hybrid solar cells. CsxMA1−xPbI3 perovskite devices with an optimized 10% Cs doping concentration exhibit remarkable improvement in device efficiency from 5.51% to 7.68% due to increases in short-circuit current density and open-circuit voltage via increased light absorption at optimum device thickness, improved film morphology and a widening of the energy difference between the valence band of the perovskite and lowest unoccupied molecular orbital level of PCBM.