Tellurium-Based Double Perovskites A2TeX6 with Tunable Band Gap and Long Carrier Diffusion Length for Optoelectronic Applications

Abstract
Lead-free hybrid perovskites have attracted immense interest as environmentally friendly light absorbers. Here, we report on tellurium (Te)-based double perovskites A2TeX6 (A = MA, FA, or BA; X = Br– or I–; MA = CH3NH3; FA = CH(NH2)2; BA = benzylamine) as potentially active materials for optoelectronic devices. These perovskites exhibit a tunable band gap (1.42–2.02 eV), a low trap density (∼1010 cm–3), and a high mobility (∼65 cm2 V–1 s–1). Encouragingly, the MA2TeBr6 single crystal with a band gap of 2.00 eV possesses a long carrier lifetime of ∼6 μs and corresponding carrier diffusion lengths of ∼38 μm, which are ideal characteristics for a material for photodetectors and tandem solar cells. Moreover, A2TeX6 perovskites are relatively robust in ambient conditions, being stable for at least two months without showing any signs of phase change. Our findings bring to the forefront a family of lead-free Te-based perovskites for nontoxic perovskite optoelectronics.

Citation
Ju D, Zheng X, Yin J, Qiu Z, Türedi B, et al. (2018) Tellurium-Based Double Perovskites A2TeX6 with Tunable Band Gap and Long Carrier Diffusion Length for Optoelectronic Applications. ACS Energy Letters: 228–234. Available: http://dx.doi.org/10.1021/acsenergylett.8b02113.

Acknowledgements
This work was supported by the National Natural Science Foundation of China (Grant Nos. 51321091, 51772170, 51272129, and 51227002), National Key Research and Development Program of China (Grant No. 2016YFB1102201), the Program of Introducing Talents of Disciplines to Universities in China (111 Project 2.0 (Grant No. BP2018013), and King Abdullah University of Science and Technology (KAUST). We greatly thank Xiufeng Cheng and Zhaozhen Cao for their help in thermal properties and TRPL measurements, respectively.

Publisher
American Chemical Society (ACS)

Journal
ACS Energy Letters

DOI
10.1021/acsenergylett.8b02113

Additional Links
https://pubs.acs.org/doi/10.1021/acsenergylett.8b02113

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