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Title: Towards understanding the doping mechanism of organic semiconductors by Lewis acids

Journal Article · · Nature Materials

Precise doping of organic semiconductors allows control over the conductivity of these materials, an essential parameter in electronic applications. Although Lewis acids have recently shown promise as dopants for solution-processed polymers, their doping mechanism is not yet fully understood. In this study, we found that B(C6F5)3 is a superior dopant to the other Lewis acids investigated (BF3, BBr3 and AlCl3). Experiments indicate that Lewis acid–base adduct formation with polymers inhibits the doping process. Electron–nuclear double-resonance and nuclear magnetic resonance experiments, together with density functional theory, show that p-type doping occurs by generation of a water–Lewis acid complex with substantial Brønsted acidity, followed by protonation of the polymer backbone and electron transfer from a neutral chain segment to a positively charged, protonated one. Here, this study provides insight into a potential path for protonic acid doping and shows how trace levels of water can transform Lewis acids into powerful Brønsted acids.

Research Organization:
Univ. of California, Santa Barbara, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; National Science Foundation (NSF); German Research Foundation (DFG)
Grant/Contract Number:
SC0017659; SC0018208; AC02-05CH11231
OSTI ID:
1593929
Journal Information:
Nature Materials, Journal Name: Nature Materials Journal Issue: 12 Vol. 18; ISSN 1476-1122
Publisher:
Springer Nature - Nature Publishing GroupCopyright Statement
Country of Publication:
United States
Language:
English

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