Vibronic coherence contributes to photocurrent generation in organic semiconductor heterojunction diodes

Qingzhen Bian*, Fei Ma, Shula Chen, Qi Wei, Xiaojun Su, Irina A. Buyanova, Weimin M. Chen, Carlito S. Ponseca, Mathieu Linares, Khadga J. Karki, Arkady Yartsev, Olle Inganäs

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Charge separation dynamics after the absorption of a photon is a fundamental process relevant both for photosynthetic reaction centers and artificial solar conversion devices. It has been proposed that quantum coherence plays a role in the formation of charge carriers in organic photovoltaics, but experimental proofs have been lacking. Here we report experimental evidence of coherence in the charge separation process in organic donor/acceptor heterojunctions, in the form of low frequency oscillatory signature in the kinetics of the transient absorption and nonlinear two-dimensional photocurrent spectroscopy. The coherence plays a decisive role in the initial ~200 femtoseconds as we observe distinct experimental signatures of coherent photocurrent generation. This coherent process breaks the energy barrier limitation for charge formation, thus competing with excitation energy transfer. The physics may inspire the design of new photovoltaic materials with high device performance, which explore the quantum effects in the next-generation optoelectronic applications.

Original languageEnglish
Article number617
JournalNature Communications
Volume11
Issue number1
DOIs
StatePublished - 1 Dec 2020
Externally publishedYes

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