High photocurrent PbSe solar cells with thin active layers

Thin active layers in solar cells normally have lower defect density with easier procedure and lower cost than thick ones. PbSe nanocrystal (NC)-based solar cells with thin layers were fabricated using a ligand exchange procedure. An optical spacer was confirmed to be effective in improving the distribution of light field in the devices, which could enhance the photon absorption of the thin active layers. Meanwhile, the transportation of electrons and holes was balanced and optimized by tuning the particle size and the layer thickness, which demonstrated a high short-circuit current of 32.2 mA cm−2 and a 1 sun power conversion efficiency of 4.12%. Besides, the devices with smaller PbSe NCs preserved the high efficiency for tens of hours, which is different from previous studies using large NCs.