Charge generation and energy transfer in hybrid polymer/infrared quantum dot solar cells

• DOI: 10.1039/c2ee24175g
• Publication Date: 2013-01-04T12:32:40Z
• Authors: Elisabeth Strein; Adam Colbert; Selvam Subramaniyan; Hirokazu Nagaoka; Cody W. Schlenker; Eric Janke; Samson A. Jenekhe; David S. Ginger
• Keywords: Photocurrent; Quantum Efficiency; Thiazole; Hybrid solar cell

Conjugated polymers blended with nanocrystal quantum dots are interesting as solution processable active layers for infrared light harvesting in thin film solar cells. We study photocurrent generation processes hybrid polymer/quantum dot photovoltaics by comparing device performance and photoinduced absorption (PIA) spectra across blends of three different conjugated polymers, poly(2,3-bis(2-(hexyldecyl)-quinoxaline-5,8-diyl-alt-N-(2-hexyldecyl)-dithieno[3,2-b:2′,3′-d]pyrrole) (PDTPQx-HD), poly[(4,4′-bis(3-(2-hexyl-decyl)dithieno[3,2-b:2′,3′-d]pyrrole)-2,6-diyl-alt-(2,5-bis(3-(2-ethyl-hexyl)thiophen-2yl)thiazolo[5,4-d]thiazole)] (PPEHTT), poly[(4,4′-bis(2-octyl)dithieno[3,2-b:2′3′-d]silole)-2,6-diyl-alt-(2,5-bis(3-octylthiophen-2yl)thiazolo[5,4-d]thiazole)] (PSOTT) PbS dots. The PIA provide evidence long-lived charge separation bulk heterojunction operation both PDTPQx-HD PPEHTT PbS. In contrast we find that PSOTT/PbS can produce viable cells without any transfer the spectra. Even so, external efficiency (EQE) indicate polymer plays a significant role harvesting. use photoluminescence excitation spectroscopy to confirm funnels energy via transfer, speculate these may operate Schottky diodes sensitized from semiconducting host.