3 years ago

Ultralow Self-Doping in Two-dimensional Hybrid Perovskite Single Crystals

Ultralow Self-Doping in Two-dimensional Hybrid Perovskite Single Crystals
Chao Shen, Edward Sargent, Boon S. Ooi, Banavoth Murali, Michele De Bastiani, Wei Peng, Olivier Ouellette, Xiaohe Miao, Osman M. Bakr, Jun Pan, Omar El Tall, Kang-Ting Ho, Omar F. Mohammed, Jun Yin, Erkki Alarousu, Jr-Hau He
Unintentional self-doping in semiconductors through shallow defects is detrimental to optoelectronic device performance. It adversely affects junction properties and it introduces electronic noise. This is especially acute for solution-processed semiconductors, including hybrid perovskites, which are usually high in defects due to rapid crystallization. Here, we uncover extremely low self-doping concentrations in single crystals of the two-dimensional perovskites (C6H5C2H4NH3)2PbI4·(CH3NH3PbI3)n−1 (n = 1, 2, and 3), over three orders of magnitude lower than those of typical three-dimensional hybrid perovskites, by analyzing their conductivity behavior. We propose that crystallization of hybrid perovskites containing large organic cations suppresses defect formation and thus favors a low self-doping level. To exemplify the benefits of this effect, we demonstrate extraordinarily high light-detectivity (1013 Jones) in (C6H5C2H4NH3)2PbI4·(CH3NH3PbI3)n−1 photoconductors due to the reduced electronic noise, which makes them particularly attractive for the detection of weak light signals. Furthermore, the low self-doping concentration reduces the equilibrium charge carrier concentration in (C6H5C2H4NH3)2PbI4·(CH3NH3PbI3)n−1, advantageous in the design of p–i–n heterojunction solar cells by optimizing band alignment and promoting carrier depletion in the intrinsic perovskite layer, thereby enhancing charge extraction.

Publisher URL: http://dx.doi.org/10.1021/acs.nanolett.7b01475

DOI: 10.1021/acs.nanolett.7b01475

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