Revealing molecular conformation-induced stress at embedded interfaces of organic optoelectronic devices by sum frequency generation spectroscopy

Zhongwu Wang; Hongzhen Lin; Xi Zhang; Jie Li; Xiaosong Chen; Shuguang Wang; Wenbin Gong; Hui Yan; Qiang Zhao; Weibang Lv; Xue Gong; Qingbo Xiao; Fujin Li; Deyang Ji; Xiaotao Zhang; Huanli Dong; Liqiang Li; Wenping Hu

doi:10.1126/sciadv.abf8555

Revealing molecular conformation-induced stress at embedded interfaces of organic optoelectronic devices by sum frequency generation spectroscopy

Sci Adv. 2021 Apr 14;7(16):eabf8555. doi: 10.1126/sciadv.abf8555. Print 2021 Apr.

Authors

Zhongwu Wang¹, Hongzhen Lin², Xi Zhang³, Jie Li¹, Xiaosong Chen¹, Shuguang Wang¹, Wenbin Gong², Hui Yan⁴, Qiang Zhao⁵, Weibang Lv², Xue Gong², Qingbo Xiao², Fujin Li², Deyang Ji¹, Xiaotao Zhang¹, Huanli Dong³, Liqiang Li^{6

2

7}, Wenping Hu^{1

3

7}

Affiliations

¹ Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, Institute of Molecular Aggregation Science, Tianjin University, Tianjin 300072, China.
² Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China.
³ Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
⁴ School of Pharmaceutical Sciences, Liaocheng University, Liaocheng 252059, China.
⁵ College of Science, Civil Aviation University of China, Tianjin 300300, China.
⁶ Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, Institute of Molecular Aggregation Science, Tianjin University, Tianjin 300072, China. lilq@tju.edu.cn.
⁷ Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Fuzhou 350207, China.

Abstract

Interface stresses are pervasive and critical in conventional optoelectronic devices and generally lead to many failures and reliability problems. However, detection of the interface stress embedded in organic optoelectronic devices is a long-standing problem, which causes the unknown relationship between interface stress and organic device stability (one key and unsettled issue for practical applications). In this study, a kind of previously unknown molecular conformation-induced stress is revealed at the organic embedded interface through sum frequency generation (SFG) spectroscopy technique. This stress can be greater than 10 kcal/mol per nm² and is sufficient to induce molecular disorder in the organic semiconductor layer (with energy below 8 kcal/mol per nm²), finally causing instability of the organic transistor. This study not only reveals interface stress in organic devices but also correlates instability of organic devices with the interface stress for the first time, offering an effective solution for improving device stability.

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