Navigating the relationship between voltage losses and efficiency in organic solar cellsShow others and affiliations
2025 (English)In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 140, article id 107211Article in journal (Refereed) Published
Abstract [en]
In recent years, organic solar cells (OSCs) have made significant progress, with power conversion efficiencies over 20 %, mainly due to advances in non-fullerene acceptors. Nevertheless, high voltage losses- especially those caused by non-radiative recombination- remain a major obstacle to further efficiency improvements. In contrast to traditional fullerene-based OSCs, state-of-the-art non-fullerene OSCs enable efficient charge generation and extraction even at small energy offsets (<0.3 eV) between the HOMO levels of the donor and the acceptor materials (Delta HOMO). However, achieving low voltage loss while maintaining high fill factor and shortcircuit current (Jsc) is a major challenge due to inherent trade-offs. In this study, we systematically investigate the relationship between voltage losses and the other two parameters in nine non-fullerene OSC devices with Delta HOMO in the range of about 0-0.5 eV. Both radiative and non-radiative voltage losses show a clear increase with Delta HOMO. However, no general correlation was found between the voltage loss, Jsc and FF. Only poorly performing IDTBR-based devices show clear increase of Jsc with Delta HOMO, which, according to the transient absorption data, is caused by inefficient charge generation at low Delta HOMO attributable to high exciton binding energy or inferior molecule packing. At the same time, the opposite trend is observed for well-performing blends. These features suggest that variations of other blend parameters rather Delta HOMO cause variations of Jsc and FF overwhelming dependence on Delta HOMO.
Place, publisher, year, edition, pages
ELSEVIER , 2025. Vol. 140, article id 107211
Keywords [en]
Organic solar cells; Charge generation; Voltage loss; Transient absorption; Non-fullerene acceptors
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Other Physics Topics
Identifiers
URN: urn:nbn:se:liu:diva-212280DOI: 10.1016/j.orgel.2025.107211ISI: 001436303900001Scopus ID: 2-s2.0-85217743825OAI: oai:DiVA.org:liu-212280DiVA, id: diva2:1945183
2025-03-182025-03-182025-04-17