High-Efficiency Colloidal Quantum Dot Photovoltaic Devices Using Chemically Modified Heterojunctions

High-efficiency colloidal quantum dot photovoltaic devices (CQDPVs) are achieved by improving the interfacial charge extraction via chemical modification of PbS-CQD/ZnO heterojunctions. Simple treatment of the heterojunctions using a chemical modifier, 1,2-ethanedithiol, effectively reduces the interband trap sites of the ZnO nanoparticles (ZnO-np) by passivation of the notorious intrinsic oxygen-deficient defects. As a result, the interfacial bimolecular recombinations between (i) trapped electrons in the ZnO-np layers and the holes in the CQD layers and (ii) accumulated electrons in the CQD layers and the holes in the CQD layers are suppressed. Consequently, the power conversion efficiency of the chemically modified CQDPVs reached a certified power conversion efficiency of 10.14% with decent air stability. Notably, the entire device fabrication process, including chemical modification, could be performed at room temperature under ambient atmosphere.