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Unconventional electrochromism in boron arsenide crystal induced by charge symmetry enhancement
Jianchao Li1, Penghui Li2, Zhanjun Qiu1
1School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510006, China.
Abstract:
Electrochromism encompasses phenomena where materials undergo color changes in response to electricity. Conventional understanding attributes electrochromism to redox reactions occurring between phases with distinct band structures. We report an unconventional electrochromic mechanism in boron arsenide (BAs) crystals that challenges this traditional paradigm. Upon application of several volts, these crystals exhibit rapid color transformation from transparent-red to black, reverting to original color upon voltage removal. Comprehensive structural characterization reveals that this color modulation originates from electromechanical effects rather than redox reactions. Specifically, the observed band gap narrowing stems from strain-induced charge symmetry enhancement within BAs. This discovery not only expands the fundamental understanding of electrochromic mechanisms but also establishes BAs as a unique semiconductor exhibiting exceptional physical properties beyond its reported thermal and electrical transport characteristics.
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