Thermal Properties of TiO2/PbS Nanoparticle Solar Cells

Photovoltaic performance is shown to depend on ligand capping on PbS nanoparticle solar cells by varying the temperature between 140K and 350K. The thermal response of open‐circuit voltage, short‐circuit current density, fill‐factor and shunt resistance varies between the ligands. A large increase in short‐circuit current density at low temperatures is observed for 1,2‐ethanedithiol and 3‐mercaptopropionic acid and a relatively constant shortcircuit current density is observed for the stiffer 1,4‐benzenedithiol. Dark data provide evidence for tunnelling transport being the dominant charge conduction mechanism for all three ligand devices with recombination occurring within deep trap states. Under illumination, devices exhibit band‐to‐band recombination, indicated by an ideality factor of nearly unity.