Controlled Substitution of Chlorine for Iodine in Single-Crystal Nanofibers of Mixed Perovskite MAPbI_3-xCl_x

Abstract

Longer carrier diffusion length and improved power conversion efficiency have been reported for thin-film solar cell of organolead mixed-halide perovskite MAPbI3- x Cl x in comparison with MAPbI3 . Instead of substituting I in the MAPbI3 lattice, Cl-incorporation has been shown to mainly improve the film morphology of perovskite absorber. Well-defined crystal structure, adjustable composition (x), and regular morphology, remains a formidable task. Herein, a facile solution-assembly method is reported for synthesizing single-crystalline nanofibers (NFs) of tetragonal-lattice MAPbI3- x Cl x with the Cl-content adjustable between 0 ≤ x ≤ 0.75, leading to a gradual blueshift of the absorption and photoluminescence maxima from x = 0 to 0.75. The photoresponsivity (R) of MAPbI3 NFs keeps almost unchanging at a value independent of the white-light illumination intensity (P). In contrast, R of MAPbI3- x Cl x NFs decreases rapidly with increasing both the x and P values, indicating Cl-substitution increases the recombination traps of photogenerated free electrons and holes. This study provides a model system to examine the role of extrinsic Cl ions in both perovskite crystallography and optoelectronic properties.

The Role of Chloride Incorporation in Lead‐Free 2D Perovskite (BA)2SnI4: Morphology, Photoluminescence, Phase Transition, and Charge Transport

“…In the experimental aspect, it is widely reported that the XRD patterns of the Cl doped MAPbI 3− x Cl x films have the same diffraction peaks as that of pure MAPbI 3 films and no ClPb bonds has been observed from XPS spectrum of MAPbI 3− x Cl x films, both of which suggest that the Cl element is not truly incorporated into the crystal lattice of MAPbI 3 . Nevertheless, we found that the diffraction peaks in our (BA) 2 SnI 4− x Cl x crystals gradually shift to the smaller angles as the ratio of I to Cl in precursor increases, which agrees with previous reports and suggests that the Cl element has been successfully doped into the crystal lattice of (BA) 2 SnI 4 ( Figure a and Figure S1, Supporting Information). The Cl incorporation leads to the lattice distortion, resulting in the shift of the diffraction peaks.…”

Recent Advances in Halide Perovskite Photodetectors Based on Different Dimensional Materials

“…Recently, mixed perovskite MAPbI 3− x Cl x has been thought to possess longer carrier diffusion length and lifetimes than undoped MAPbI 3 . To better investigate the role of chloride ions in perovskite crystallography and optoelectronic properties, Zhang et al conducted research on Cl/I mixed perovskite (MAPbI 3− x Cl x ). By analyzing the d ‐spacing of the crystal and the characterization results, they found that the substitution of Cl for I occurs at I flank positions rather than at I top positions.…”

First Principles Computation on the Photovoltaic and Thermoelectric Properties of MAPbI3-xClx Perovskites

“…The simulation molecular model of the MAPbI3-xClx with tetragonal lattice structure is shown in Figure 1. The Cl substitution position is still unknown, however the recent experiment reported that it occurs at the equatorial position rather than the apical position [7]. Through this study, we intend to understand the effect of Cl doping on MAPbI3-xClx photovoltaic and thermoelectric properties and thus will develop a better solar thermoelectric device in the future.…”