Understanding the Interplay of Transport-Morphology-Performance in PBDB-T-Based Polymer Solar Cells

Journal article

Authors/Editors

NOPPORN RUJISAMPHAN

Strategic Research Themes

Sustainable Energy & Environment (Strategic Research Themes)

Publication Details

Author list: Zhang Q., Yuan X., Feng Y., Larson B.W., Su G.M., Maung Maung Y., Rujisamphan N., Li Y., Yuan J., Ma W.

Publisher: Wiley

Publication year: 2020

Journal: physica status solidi - Rapid Research Letters (1862-6254)

Volume number: 4

Issue number: 4

ISSN: 1862-6254

eISSN: 1862-6270

URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083501952&doi=10.1002%2fsolr.201900524&partnerID=40&md5=a907759f88eb1e73d79bd04a4eb51114

Languages: English-Great Britain (EN-GB)

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Abstract

Polymer–polymer blends have been reported to exhibit exceptional thermal and ambient stability. However, power conversion efficiencies (PCEs) from devices using polymeric acceptors have been recorded to be significantly lower than those based on conjugated molecular acceptors. Herein, two organic nonfullerene bulk heterojunction (BHJ) blends ITIC:PBDB-T and N2200:PBDB-T, together with their fullerene counterpart, PCBM:PBDB-T, are adopted to understand the effect of electron acceptors on device performance. Free charge carrier properties using time-resolved microwave conductivity (TRMC) measurements are comprehensively investigated. The nonfullerene devices show an improved PCE of 10.06% and 6.65% in the ITIC- and N2200-based cells, respectively. In comparison, the PCBM:PBDB-T-based devices yield a PCE of 5.88%. The optimal N2200:PBDB-T produced the highest TRMC mobility, longest lifetime, and greatest free-carrier diffusion length. It is found that such phenomena can be associated with the unfavorable morphology of the all-polymer BHJ microstructure. In contrast, the solar cells using either the PCBM or ITIC acceptors display a more balanced donor and acceptor phase separation, leading to more efficient free-carrier separation and transport in the operating device. By sacrificing efficiency for superior stability, it is shown that the improved structure in all-polymer blend can deliver a more stable morphology under thermal stress. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Keywords

free carrier mobility, nonfullerene acceptors, time-resolved microwave conductivity