Nanocrystal Inks for Spray-Deposited Photovoltaics

Abstract

We have been developing colloidal copper indium gallium selenide (and sulfide) (CIGS) and copper zinc tin sulfide (CZTS) nanocrystal dispersions, or inks, as precursor materials to fabricate with low cost photovoltaic solar cell devices (PVs). This presentation will discuss the synthesis of the nanocrystals and their implementation into prototype PVs. Devices with power conversion efficiencies of just over 3% under AM 1.5 illumination have been made without resorting to high temperature processing. Devices can be constructed on standard soda lime glass substrates or on mechanically flexible plastic substrates. Processing the nanocrystal absorber films by high temperature (~450 oC) selenization, efficiencies of more than 5% have been achieved. The properties of the nanocrystal films and their relationship to the observed device efficiency will be presented, along with a discussion about how to further improve the efficiencies of the nanocrystal-based devices.