Study on the Ion Substitution Mechanism of CsPbIBr₂ Films Prepared by a Drop-Coating Method

Abstract

In this paper, the ion substitution mechanism of CsPbIBr 2 films prepared by a drop-coating method is studied. CsI/ CsBr methanol solution is drop-coated on a CsPbIBr 2 precursor film to prepare the CsPbIBr 2 perovskite film. After drop-coating, it is found that the color of the perovskite film changes with CsI/ CsBr methanol solution drop-coated on the perovskite precursor film. When CsBr methanol solution is drop-coated on a CsPbIBr 2 precursor film, the color of the obtained CsPbIBr 2 film is orange. The color of the obtained CsPbIBr 2 film is brown while CsI methanol solution is drop-coated on a CsPbIBr 2 precursor film. Then, the hole-free, carbon-based CsPbIBr 2 perovskite solar cells (FTO/ZnO/CsPbIBr 2 /C) are fabricated. For the solar cells fabricated by drop-coating with 30 μL of CsBr, without methanol solution, with 10 μL of CsI, with 50 μL of CsI, and with 90 μL of CsI, the power conversion efficiency (PCE) values are 2.98, 3.99, 6.04, 7.60, and 8.42%, respectively. The short-circuit current density (J SC ) also increases with the changing of drop-coating solution. Therefore, we suppose that perhaps there is an ion substitution during the preparation of the CsPbIBr 2 films. The ion substitution supposition is verified by the results of X-ray diffraction, ultraviolet−visible spectra, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy. Specifically, the I element is replaced by the Br element while drop-coating CsBr methanol solution. The Br element is substituted by the I element by drop-coating CsI methanol solution. Also, it is verified that the ion substitution occurs in the entire perovskite film.

Solution microcrystal enables a high-quality CsPbIBr2 film to minimize intragranular charge recombination for air-stable, carbon-based photovoltaics

“…This is one of the highest efficiencies for all-inorganic CsPbIBr 2 -based PSCs reported to date (Fig. 3c and Table S2) [29][30][31][32][33][34][35][36][37][38][39][40][41][42]. Furthermore, the distribution of statistical parameters from 20 devices for each case in Fig.…”

Efficient and Stable All‐Inorganic CsPbIBr2 Perovskite Solar Cells Enabled by Dynamic Vacuum‐Assisted Low‐Temperature Engineering

“…[19] Beyond that, a smaller ideality factor n of 1.43 also demonstrates that trap-assisted recombination is effectively suppressed in VALT-CsPbIBr 2 PSCs versus that of HT-CsPbIBr 2 ones (1.98). [52] Furthermore, the trap-state densities (N t ) of optimized devices were investigated via devices with the structure of ITO/ZnO/ CsPbIBr 2 /PCBM/Ag according to the space charge-limited current (SCLC) method. In general, the J-V curves of the abovementioned devices present three different regions, where the linear part in the lower voltage and the nonlinear section in the larger voltage correspond to the ohmic contact region and trap-filled region, respectively.…”

“…[ 19 ] Beyond that, a smaller ideality factor n of 1.43 also demonstrates that trap‐assisted recombination is effectively suppressed in VALT‐CsPbIBr 2 PSCs versus that of HT‐CsPbIBr 2 ones (1.98). [ 52 ]…”

Recent Progress of Carbon‐Based Inorganic Perovskite Solar Cells: From Efficiency to Stability

“…In addition, several novel strategies have also been attempted to fabricate CsBX 3 , such as annealing process optimization, [37,130,[166][167][168][169] spray-coating process, [170,171] intermediate phase assisted sequential deposition, [172] gradient cooling process, [173] benign pinholes, [162] light-processing technology, [159] substrate optimization (moth-eye antireflector and muscovite), [174,175] fluxmediated crystal growth strategy, [176] drop-coating method, [177] halide exchange, [178] direct molecule substitution, [179] ambient environment fabrication, [117,180] phase transition induced method, [131] two-step infiltration-spinning method, [181] mist deposition method, [182] hybrid CVD (HCVD), [183] single-source electron beam evaporation, [183,184] UV-ozone post-treatment, [185] air blowing recipe, [186] two-step sintering (TSS) method, [133] electrodeposition, [187] hot-flow-assisted spin-coating approach, [39] intermolecular exchange strategy, [188] hot-pressing method, [189] and so on.…”