Order enables efficient electron-hole separation at an organic heterojunction with a small energy loss

S. Matthew Menke, Alexandre Cheminal, Patrick Conaghan, Niva A. Ran, Neil C. Greehnam, Guillermo C. Bazan, Thuc-Quyen Nguyen, Akshay Rao, Richard H. Friend

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

Donor–acceptor organic solar cells often show low open-circuit voltages (VOC) relative to their optical energy gap (Eg) that limit power conversion efficiencies to ~12%. This energy loss is partly attributed to the offset between Eg and that of intermolecular charge transfer (CT) states at the donor–acceptor interface. Here we study charge generation occurring in PIPCP:PC61BM, a system with a very low driving energy for initial charge separation (Eg−ECT ~ 50 meV) and a high internal quantum efficiency (ηIQE ~ 80%). We track the strength of the electric field generated between the separating electron-hole pair by following the transient electroabsorption optical response, and find that while localised CT states are formed rapidly (
Original languageEnglish (US)
JournalNature Communications
Volume9
Issue number1
DOIs
StatePublished - Jan 18 2018
Externally publishedYes

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