Control of Electrical Potential Distribution for High-Performance Perovskite Solar Cells

The electrical potential distribution within photovoltaic devices plays critical roles in governing charge carrier dynamics and the device performance. Here we present the electrical potential distribution within highly efficient perovskite solar cells (PSCs) in working status. We found the major potential drop existing at the perovskite/mesoporous TiO2 interface, indicating one diode junction in mesoporous PSCs. In contrast, the major potential drop was found on both sides of the perovskite layer in planar PSCs, exhibiting two diode junctions where the charge carriers could be recombined more easily than single-junction PSCs. We further controlled the position of diode junctions in planar PSCs by changing the dopant concentration. The undesirable charge recombination was largely suppressed, which enabled a better ideality factor and a higher efficiency 20.12% for planar PSCs with the increase of donor concentration. The present study will be helpful for understanding the fundamental mechanism within PSCs and achieving high device efficiency.