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

Journal Article · Sun Aug 02 00:00:00 EDT 2020 · Advanced Energy Materials

DOI:https://doi.org/10.1002/aenm.202001589· OSTI ID:1644346

Bin, Haijun ^[1]; Angunawela, Indunil ^[2]; Qiu, Beibei ^[3]; Colberts, Fallon J. M. ^[4]; Li, Mengmeng ^[5]; Dyson, Matthew J. ^[1]; Wienk, Martijn M. ^[1]; Ade, Harald ^[2]; Li, Yongfang ^[3]; Janssen, René A. J. ^[6]

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1. Molecular Materials and Nanosystems and Institute for Complex Molecular Systems Eindhoven University of Technology P.O. Box 513 Eindhoven 5600 MB The Netherlands
2. Department of Physics and Organic and Carbon Electronics Lab (ORaCEL) North Carolina State University Raleigh NC 27695 USA
3. Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry Chinese Academy of Sciences Beijing 100190 China
4. Energy Engineering Zuyd University of Applied Sciences Nieuw Eyckholt 300 Heerlen 6419 DJ The Netherlands
5. Molecular Materials and Nanosystems and Institute for Complex Molecular Systems Eindhoven University of Technology P.O. Box 513 Eindhoven 5600 MB The Netherlands, Dutch Institute for Fundamental Energy Research De Zaale 20 Eindhoven 5612 AJ The Netherlands, Key Laboratory of Microelectronic Devices and Integrated Technology Institute of Microelectronics Chinese Academy of Sciences Beijing 100029 China
6. Molecular Materials and Nanosystems and Institute for Complex Molecular Systems Eindhoven University of Technology P.O. Box 513 Eindhoven 5600 MB The Netherlands, Dutch Institute for Fundamental Energy Research De Zaale 20 Eindhoven 5612 AJ The Netherlands

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.

• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1644346
• Alternate ID(s): OSTI ID: 1644349
• Journal Information: Advanced Energy Materials, Journal Name: Advanced Energy Materials Journal Issue: 34 Vol. 10; ISSN 1614-6832
• Publisher: Wiley Blackwell (John Wiley & Sons)
• Country of Publication: Germany
• Language: English