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Hole Transfer from Low Band Gap Quantum Dots to Conjugated Polymers in Organic/Inorganic Hybrid Photovoltaics

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journal contribution
posted on 2015-12-16, 22:20 authored by Adam E. Colbert, Eric M. Janke, Stephen T. Hsieh, Selvam Subramaniyan, Cody W. Schlenker, Samson A. Jenekhe, David S. Ginger
We use photoinduced absorption (PIA) spectroscopy to investigate pathways for photocurrent generation in hybrid organic/inorganic quantum dot bulk heterojunction solar cells. We study blends of the conjugated polymer poly­(2,3-bis­(2-(hexyldecyl)­quinoxaline-5,8-diyl-alt-N-(2-hexyldecyl)­dithieno­[3,2-b:2′,3′-d]­pyrrole) (PDTPQx-HD) with PbS quantum dots and find that positively charged polarons are formed on the conjugated polymer following selective photoexcitation of the PbS quantum dots. This result provides a direct spectroscopic fingerprint demonstrating that photoinduced hole transfer occurs from the photoexcited quantum dots to the host polymer. We compute the relative yields of long-lived holes following photoexcitation of both the polymer and quantum dot phases and estimate that more long-lived polarons are produced per photon absorbed by the polymer phase than by the quantum dot phase.