Final Report for DE-FG36-08GO18007 "All-Inorganic, Efficient Photovoltaic Solid State Devices Utilizing Semiconducting Colloidal Nanocrystal Quantum Dots"

Abstract

Executive Summary: We demonstrated robust colloidal quantum dot (QD) photovoltaics with high internal quantum efficiencies. In our structures, device durability is derived from use of all-inorganic atmospherically-stable semiconducting metal-oxide films together with QD photoreceptors. We have shown that both QD and metal-oxide semiconducting films and contacts are amenable to room temperature processing under minimal vacuum conditions, enabling large area processing of PV structures of high internal efficiency. We generated the state of the art devices with power conversion efficiency of more than 4%, and have shown that efficiencies as high as 9% are achievable in the near-term, and as high as 17% in the long-term. Motivation and Outcomes:Considerable interest in the incorporation of colloidal QDs and other quantum-confined semiconductor structures into photovoltaics (PVs) is due to their broad spectral tunability, strong optical absorption, and ease of processing. QDs made from the II-VI materials such as CdS, CdSe, and CdTe can be tuned in the visible, while IV-VI materials such as PbS and PbSe exhibit band-edge responses in the IR, even beyond λ = 2000 nm wavelength. As solution processable perfect crystals of tunable band gap, colloidal QD-PVs have a remarkable potential to advance the photovoltaic technology.