Negligible Energy Loss during Charge Generation in Small-Molecule/Fullerene Bulk-Heterojunction Solar Cells Leads to Open-Circuit Voltage over 1.10 v

Maxime Babics, Tainan Duan*, Ahmed H. Balawi, Ru Ze Liang, Federico Cruciani, Ionela Daniela Carja, Dale Gottlieb, Iain McCulloch, Koen Vandewal, Frédéric Laquai, Pierre M. Beaujuge

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Solution-processable small molecules (SMs) that can serve as donors in bulk-heterojunction (BHJ) solar cells are practical alternatives to their polymer counterparts. However, SM-fullerene blends commonly suffer severe voltage losses. In general, devices that reach open-circuit voltages (VOC) > 1 V yield low photocurrents in BHJ solar cells with fullerene acceptors (e.g., PC71BM) and modest power conversion efficiencies (PCEs). In this contribution, we report on the design, synthesis, and BHJ device characteristics of a new SM donor, 2F-DRCN5T, yielding a VOC of up to 1.10 V with PC71BM as the fullerene acceptor, while maintaining PCEs > 7% (over 8% achieved upon solvent-vapor-annealing (SVA) treatment). The negligible energy loss during charge generation (ΔECT), the deep-lying HOMO of 2F-DRCN5T inferred from its large ionization potential (IP), the high charge-transfer-state energy (ECT) of the blend, and a reduced nonradiative voltage loss account for the high VOC achieved in BHJ solar cells.

Original languageEnglish (US)
Pages (from-to)2717-2722
Number of pages6
JournalACS Applied Energy Materials
Volume2
Issue number4
DOIs
StatePublished - Apr 22 2019

Bibliographical note

Funding Information:
This publication is based upon work supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Award CRG-R2-13-BEAU-KAUST-1. The authors acknowledge concurrent support under Baseline Research Funding from KAUST. T.D. acknowledges financial support from National Natural Science Foundation of China (21702202).

Funding Information:
This publication is based upon work supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Award CRG_R2_13_BEAU_KAUST_1. The authors acknowledge concurrent support under Baseline Research Funding from KAUST. T.D. acknowledges financial support from National Natural Science Foundation of China (21702202).

Publisher Copyright:
© 2019 American Chemical Society.

Keywords

  • fluorination
  • high open-circuit voltage
  • low energy loss
  • oligothiophene
  • organic photovoltaics
  • small-molecule donor

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Energy Engineering and Power Technology
  • Electrochemistry
  • Materials Chemistry
  • Electrical and Electronic Engineering

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