Researchers from the University of North Carolina at Chapel Hill, University of Toledo and Perotech Energy have found that bathocuproine, which is often used as an electron-transport material, can improve power-conversion efficiency and stability when added to the hole-transport layer.
The chelation product of bathocuproine with lead ions is insoluble in the perovskite ink and also decreases the formation of amorphous regions by reducing the amount of trapped dimethyl sulfoxide solvent. Minimodules with an aperture area of 26.9 square centimeters had a certified efficiency of 21.8% and light-soaking stability exceeding 2000 hours.
Defective bottom interfaces of perovskites and hole-transport layers (HTLs) tend to limit the performance of p-i-n structure perovskite solar cells. The team in this recent work report that the addition of lead chelation molecules into HTLs can strongly interact with lead(II) ion (Pb2+), resulting in a reduced amorphous region in perovskites near HTLs and a passivated perovskite bottom surface.
The minimodule with an aperture area of 26.9 square centimeters has a power conversion efficiency (PCE) of 21.8% (stabilized at 21.1%) that is certified by the National Renewable Energy Laboratory (NREL), which corresponds to a minimal small-cell efficiency of 24.6% (stabilized 24.1%) throughout the module area.
Small-area cells and large-area minimodules with lead chelation molecules in HTLs had a light soaking stability of 3010 and 2130 hours, respectively, at an efficiency loss of 10% from the initial value under 1-sun illumination and open-circuit voltage conditions.