A series of chiral stereoisomers of electron transporting materials with two chiral substituents is rationally designed and synthesized, and the influence of stereoisomerism on their physical and electronic properties is investigated to demonstrate highly efficient and stable perovskite solar cells (PSCs). Compared to mesomeric naphthalene diimide (NDI) derivatives, which have heterochiral side groups with centrosymmetric molecular packing of symmetric-shaped conformers in the crystalline state, enantiomeric NDI derivatives have homochiral side groups that exhibit non-centrosymmetric molecular packing of asymmetric-shaped conformers in the crystalline state and exhibit better solution processability based on one order of magnitude higher solubility. A similar trend is observed in different rylene diimide stereoisomers based on larger semiconducting core perylene diimide. The PSCs based on NDI enantiomers with good film-forming ability and a very high lowest phase transition temperature (Tlowest) of 321 °C exhibit a high and uniform average power conversion efficiency (PCE) of 19.067 ± 0.654%. These PSCs also have a high temporal device stability, with less than 10% degradation of the PCE at 100 °C for 1000 h without encapsulation. Therefore, chiral stereoisomer engineering of charge transporting materials is a potential approach to achieve high solution processability, excellent performance, and significant temporal stability in organic electronic devices.
Bibliographical noteFunding Information:
S.‐K.J. and J.H.H. contributed equally to this work. This work was supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning and the Ministry of Education (Nos. 2014R1A5A1009799, 2018R1D1A1B07047645, 2019R1A6A1A11051471, and 2019K1A3A1A14057973) and the Ministry of Trade Industry & Energy, Republic of Korea (New & Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) (No. 20183010013820)). X‐ray structural analysis was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2019R1I1A2A01058066).
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- electron transporting materials
- perovskite solar cells
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics