Fabrication of flexible all-inorganic nanocrystal solar cells by room-temperature processing

We demonstrate the fabrication of all-inorganic heterostructured n-p junction devices made of colloidal PbS quantum dots (QDs) and TiO2 nanorods (NRs). The entire device fabrication procedure relies on room-temperature processing, which is compatible with flexible plastic substrates and low-cost production. Through Kelvin Probe Force Microscopy and femtosecond pump and probe spectroscopy we decipher the electron transfer process occurring at the interface between the colloidal PbS QDs and TiO2 anatase NRs. Overall we demonstrate a high power conversion efficiency of similar to 3.6% on glass and similar to 1.8% on flexible substrates, which is among the highest reported for entirely inorganic-nanocrystal based solar cells on plastic supports.