Bandgap Narrowing in Bi-Doped CH₃NH₃PbCl₃Perovskite Single Crystals and Thin Films

Abstract

Single crystals of heterovalent Bi-doped CH3NH3PbCl3 perovskite have been successfully grown through the inverse temperature crystallization method. Bandgap narrowing of 300 meV (a 55 nm red-shifting absorption edge) is obtained for the nominal 20% Bi-doped crystal with the host structure and the energy at the top of the valence band invariable. It is observed that the contact between the Au electrodes and single crystals transforms from Ohmic to Schottky, and the conductivity increases with increasing Bi doping level. By contrast, the Bi-doped CH3NH3PbCl3 thin films are also prepared, and the similar bandgap narrowing is found, although the narrowing degree is less than that in single crystals. This work has a comprehensive understanding of Bi-doped single crystals and thin films, providing further optoelectronic applications for these promising solution-processed hybrid perovskite semiconductor materials.

Understanding the Impact of Bismuth Heterovalent Doping on the Structural and Photophysical Properties of CH3NH3PbBr3 Halide Perovskite Crystals with Near‐IR Photoluminescence

“…[28] Figure 2a shows UV/Vis/NIR spectra of MA(Pb 1Àx Bi x )Br 3 (x = 0-0.1) with different Bi/Pb ratios. In accordance with previous studies, [14,20,29,30] the absorptionc utoffd isplays ap rogressive redshift with increasing concentration of Bi 3 + .A tt he highest doping ratio (10 %), the cutoff ends at l % 680 nm, which is shifted by about 100 nm with respect to the pristine crystal with ac utoffa tl % 580 nm. With the systematic change of absorptionc utoffs, the absorption of MA(Pb 1Àx Bi x )Br 3 (x = 0-0.1) nearly covers the whole visibles pectrum.…”

“…Recently,s trategies basedo nh eterovalent doping have been proposed to achieve modulations of electricaland optical behavior in halide perovskites. [12][13][14][15][16][17][18] It has been shownt hat the introduction of heterovalent Bi 3 + into methyl bromide based perovskite (MAPbBr 3 )p recursor solutionsc ould lead to charge doping of MAPbBr 3 . [19][20][21] The success in Bi 3 + -based doping benefits from the ease of Bi 3 + entering the octahedral cages becauseo ft he analogous electronic structures of Bi 3 + with Pb 2 + and an appropriate Goldschmidt tolerance factor (0.889).…”

Bismuth doped lead-free two-dimensional tin based halide perovskite single crystals

“…Recently, heterovalent-metal doping, which is widely used in semiconductors for bandgap and conduction type engineering, has received intensive attention as an efficient method to tailor the optoelectronic properties of the famous organic-inorganic hybrid halide perovskites [1][2][3][4][5][6][7][8][9][10][11] . For instance, trivalent element Bi 3 + doping into the lattice of APbX 3 (A = CH 3 NH 3 , Cs; X = I, Br, Cl) perovskites can enhance the light absorption at long-wavelength region [6,8,10,11] . It is noteworthy that most researchers have concentrated on the heterovalent doping in 3D lead halide perovskites.…”

(CH3NH3)AuX4⋅H2O (X=Cl, Br) and (CH3NH3)AuCl4: Low‐Band Gap Lead‐Free Layered Gold Halide Perovskite Materials

“…Note that the reported optical band gaps of elpasolite-typeC s 2 Au 2 X 6 are in the 1.31 eV (X=I) to 2.04 eV (X=Cl) range, [23] much lower than the reported MAPbCl 3 band gap of 2.9-3 eV. [24] The unusually small opticalb and gap of Cs 2 Au 2 I 6 is attributed to the fact that there are 5d-5d transitions between Au I and Au III with contributions from hybridized I5po rbitals. [23,25] The markedly lower band gaps of Au-based chlorides and bromides could be beneficial; typically, metal chlorides and bromides exhibit higher stability in air compared to the iodide counterparts.…”