Liang Y, Qin Y, Chen J, Xing W, Zou Y, Sun Y, Xu W, Zhu D. Band Engineering and Majority Carrier Switching in Isostructural Donor-Acceptor Complexes DPTTA-F
X TCNQ Crystals (
X = 1, 2, 4).
ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020;
7:1902456. [PMID:
32042565 PMCID:
PMC7001638 DOI:
10.1002/advs.201902456]
[Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 10/29/2019] [Indexed: 05/25/2023]
Abstract
Three isostructural donor-acceptor complexes DPTTA-F X TCNQ (X = 1, 2, 4) are investigated experimentally and theoretically. By tuning the number of F atoms in the acceptor molecules, the resulting complexes display a continuous down shift of the valence band maximum, conducting band minimum, and optical bandgap. The majority carriers convert from hole (DPTTA-F1TCNQ), balanced hole, and electron (DPTTA-F2TCNQ) to electron (DPTTA-F4TCNQ). This result shows that band engineering can be realized easily in the donor-acceptor complex systems by tuning the electron affinity of the acceptor. The bandgaps of these three complexes vary from 0.31 to 0.41 eV; this narrow bandgap feature is crucial for achieving high thermoelectric performance and the unintentional doping in DPTTA-F4TCNQ leads to the effective suppression of the bipolar cancelling effect on the Seebeck coefficient and the highest power factor.
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