Precise Control of Phase Separation Enables 12% Efficiency in All Small Molecule Solar Cells

Haijun Bin, Indunil Angunawela, Beibei Qiu, Fallon J.M. Colberts, Mengmeng Li, Matthew J. Dyson, Martijn M. Wienk, Harald Ade (Corresponding author), Yongfang Li (Corresponding author), René A.J. Janssen (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

33 Citations (Scopus)

Abstract

Compared to conjugated polymers, small-molecule organic semiconductors present negligible batch-to-batch variations, but presently provide comparatively low power conversion efficiencies (PCEs) in small-molecular organic solar cells (SM-OSCs), mainly due to suboptimal nanomorphology. Achieving precise control of the nanomorphology remains challenging. Here, two new small-molecular donors H13 and H14, created by fluorine and chlorine substitution of the original donor molecule H11, are presented that exhibit a similar or higher degree of crystallinity/aggregation and improved open-circuit voltage with IDIC-4F as acceptor. Due to kinetic and thermodynamic reasons, H13-based blend films possess relatively unfavorable molecular packing and morphology. In contrast, annealed H14-based blends exhibit favorable characteristics, i.e., the highest degree of aggregation with the smallest paracrystalline π–π distortions and a nanomorphology with relatively pure domains, all of which enable generating and collecting charges more efficiently. As a result, blends with H13 give a similar PCE (10.3%) as those made with H11 (10.4%), while annealed H14-based SM-OSCs have a significantly higher PCE (12.1%). Presently this represents the highest efficiency for SM-OSCs using IDIC-4F as acceptor. The results demonstrate that precise control of phase separation can be achieved by fine-tuning the molecular structure and film formation conditions, improving PCE and providing guidance for morphology design.

Original languageEnglish
Article number2001589
Number of pages13
JournalAdvanced Energy Materials
Volume10
Issue number34
Early online date2 Aug 2020
DOIs
Publication statusPublished - 1 Sept 2020

Funding

The research has received funding from the Netherlands Organisation for Scientific Research via the NWO Spinoza grant awarded to R.A.J.J. The authors further acknowledge funding from the Ministry of Education, Culture and Science (Gravity program 024.001.035). M.L. acknowledeges the Netherlands Organisation for Scientific Research (016.Veni.192.106) for financial support. M.D. thanks the Marie Skłodowska-Curie Actions Innovative Training Network “H2020-MSCAITN-2014 INFORM - 675867” for financial support. The work was further supported by the Ministry of Education, Culture and Science (Gravity program 024.001.035). NCSU gratefully acknowledges the support of ONR Grant No. N000141712204. X-ray data were acquired at beamlines 11.0.1.2 and 7.3.3 at the Advanced SLight Source, which is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The research has received funding from the Netherlands Organisation for Scientific Research via the NWO Spinoza grant awarded to R.A.J.J. The authors further acknowledge funding from the Ministry of Education, Culture and Science (Gravity program 024.001.035). M.L. acknowledeges the Netherlands Organisation for Scientific Research (016.Veni.192.106) for financial support. M.D. thanks the Marie Skłodowska‐Curie Actions Innovative Training Network “H2020‐MSCAITN‐2014 INFORM ‐ 675867” for financial support. The work was further supported by the Ministry of Education, Culture and Science (Gravity program 024.001.035). NCSU gratefully acknowledges the support of ONR Grant No. N000141712204. X‐ray data were acquired at beamlines 11.0.1.2 and 7.3.3 at the Advanced SLight Source, which is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE‐AC02‐05CH11231.

FundersFunder number
Marie Skłodowska‐Curie
Office of Naval ResearchN000141712204
U.S. Department of EnergyDE‐AC02‐05CH11231
Office of Science
Basic Energy Sciences
Horizon 2020 Framework Programme675867
Ministerie van Onderwijs, Cultuur en Wetenschap024.001.035
Nederlandse Organisatie voor Wetenschappelijk Onderzoek

    Keywords

    • chlorination
    • crystallization
    • organic solar cells
    • phase separation
    • small molecular donors

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