High-performance dopant-free conjugated small molecule-based hole-transport materials for perovskite solar cells

High-performance dopant-free small molecule hole-transport-materials (SM-HTMs) for perovskite solar cells (PSCs) are developed. The SM-HTMs possess appropriate energy levels with sufficient hole mobility to function as efficient HTM for PSCs without additional dopants. A low-temperature PSC (L-PSC) device using a dopant-free SM-HTM displayed a PCE of 18.09% with high air-storage stability, which is superior to a device using doped spiro-OMeTAD.240