AgInS2-ZnS Quantum Dots: Excited State Interactions with TiO2 and Photovoltaic Performance

Multinary quantum dots such as AgInS2 and alloyed AgInS2-ZnS are an emerging class of semiconductor materials for applications in photovoltaic and display devices. The nanocrystals of (AgInS2)(x)-(ZnS)(1-x) (for x = 0.67) exhibit a broad emission with a maximum at 623 nm and interact strongly with TiO2 nanostructures by injecting electrons from the excited state. The electron transfer rate constant as determined from transient absorption spectroscopy was 1.8 X 10(10) s(-1) . The photovoltaic performance was evaluated over a period of a few weeks to demonstrate the stability of AgInS2-ZnS when utilized as sensitizers in solar cells. We report a power conversion efficiency of 2.25% of our champion cell 1 month after its fabrication. The limitations of AgInS2-ZnS nanocrystals in achieving greater solar cell efficiency are discussed.