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

作者：Peng, Wei; Yin, Jun; Ho, Kang-Ting; Ouellette, Olivier; De Bastiani, Michele; Murali, Banavoth; El Tall, Omar; Shen, Chao; Miao, Xiaohe; Pan, Jun; Alarousu, Erkki; He, Jr-Hau; Ooi, Boon S.; Mohammed, Omar F.; Sargent, Edward; Bakr, Osman M.^*

来源：Nano Letters, 2017, 17(8): 4759-4767.

DOI：10.1021/acs.nanolett.7b01475

• Two-dimensional hybrid perovskites
• shallow defects
• unintentional self-doping
• photodetector
• single crystals

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)(2)PbI4 center dot(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 crystallisation 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 (10(13) Jones) in (C6H5C2H4NH3)(2)PbI4 center dot(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)(2)PbI4 center dot(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.

• 出版日期2017-8
• 单位KAUST