Open AccessBand Engineering and Majority Carrier Switching in Isostructural Donor–Acceptor Complexes DPTTA‐F X TCNQ Crystals ( X = 1, 2, 4)
Author(s) -
Liang Yingying,
Qin Yunke,
Chen Jie,
Xing Weilong,
Zou Ye,
Sun Yimeng,
Xu Wei,
Zhu Daoben
Publication year - 2020
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.201902456
Subject(s) - isostructural , acceptor , band gap , materials science , seebeck coefficient , doping , thermoelectric effect , crystallography , electron acceptor , optoelectronics , condensed matter physics , chemistry , crystal structure , photochemistry , physics , thermodynamics
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‐F 1 TCNQ), balanced hole, and electron (DPTTA‐F 2 TCNQ) to electron (DPTTA‐F 4 TCNQ). 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‐F 4 TCNQ leads to the effective suppression of the bipolar cancelling effect on the Seebeck coefficient and the highest power factor.