Issue 43, 2020

Design of narrow bandgap non-fullerene acceptors for photovoltaic applications and investigation of non-geminate recombination dynamics

Abstract

A new narrow bandgap non-fullerene electron acceptor was designed, synthesized, and characterized for near-infrared organic photovoltaics. This acceptor was compared to a structurally similar compound with systematically modified side chains, and a series of solar cells were fabricated, employing the common donor polymers PTB7-Th and PBDBT. The devices exhibited charge generation over a wide spectral range and power conversion efficiencies up to 8.1%. The non-geminate recombination dynamics were investigated and quantified via a combination of capacitance spectroscopy and transient open-circuit voltage decay measurements. The reduction of the bandgap results in increased bimolecular recombination losses, while solar cells composed of PBDBT were afflicted by stronger monomolecular, i.e. trap-assisted, recombination losses that ultimately caused the lower power conversion efficiencies of the respective devices. The latter observation could be correlated to less ordered blend film morphology.

Graphical abstract: Design of narrow bandgap non-fullerene acceptors for photovoltaic applications and investigation of non-geminate recombination dynamics

Supplementary files

Article information

Article type
Paper
Submitted
01 may 2020
Accepted
01 iyl 2020
First published
01 iyl 2020

J. Mater. Chem. C, 2020,8, 15175-15182

Author version available

Design of narrow bandgap non-fullerene acceptors for photovoltaic applications and investigation of non-geminate recombination dynamics

J. Vollbrecht, J. Lee, S. Ko, V. V. Brus, A. Karki, W. Le, M. Seifrid, M. J. Ford, K. Cho, G. C. Bazan and T. Nguyen, J. Mater. Chem. C, 2020, 8, 15175 DOI: 10.1039/D0TC02136A

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