Publication

Ultralow Self-Doping in 2D Hybrid Perovskite Single Crystals

Ultralow Self-Doping in 2D Hybrid Perovskite Single Crystals
Wei Peng, Jun Yin, Kang-Ting Ho, Olivier Ouellette, Michele De Bastiani, Banavoth Murali, Omar EL TALL, Chao Shen, Xiao-He Miao, Jun Pan, Erkki Alarousu, Jr-Hau He, Boon S. Ooi, Omar F. Mohammed, Edward H. Sargent, Osman M. Bakr
Nano Lett., 201717 (8), pp 4759–4767
Wei Peng, Jun Yin, Kang-Ting Ho, Olivier Ouellette, Michele De Bastiani, Banavoth Murali, Omar EL TALL, Chao Shen, Xiao-He Miao, Jun Pan, Erkki Alarousu, Jr-Hau He, Boon S. Ooi, Omar F. Mohammed, Edward H. Sargent, Osman M. Bakr
perovskite, single crystals, hybrid
2017

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 (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.
DOI: 10.1021/acs.nanolett.7b01475