Suppressing the Defects in CsPbI₂Br Perovskite Photovoltaic Films via a Homogeneous Cap-Mediated Annealing Strategy

Abstract

All-inorganic CsPbI2Br perovskite films offer attractive thermal stability and photophysical properties for high-performance optoelectronic devices. However, due to the rapid evaporation rate of the solvent, there are many defects, heterogeneous compositions, and pinholes in the CsPbI2Br films prepared by the common solution method. Herein, the homogeneous cap-mediated annealing strategy is successfully introduced to slow down the evaporation rate of the residual dimethyl sulfoxide solvent molecules in CsPbI2Br precursor films during thermal annealing. Compared with the conventional annealing method, the CsPbI2Br films prepared by the homogeneous cap-mediated annealing have excellent crystallinity with a pinhole-free surface. As a result, the perovskite solar cells based on the homogeneous cap-mediated annealing CsPbI2Br and carbon top electrode exhibited a power conversion efficiency (PCE) of 11.24%, which is much higher than that (4.36%) of the conventional annealing CsPbI2Br-based solar cells. Moreover, the homogeneous cap-mediated annealing strategy can also be introduced to a two-step annealing method. Because of the synergistic effect, the high-quality CsPbI2Br perovskite films with a low root-mean-square of 19.53 nm, enlarged grain size, and reduced defect density are obtained, and the champion PCE of the solar cells is further increased to 12.82%.

Additive Engineering for Mixed Lead–Tin Narrow-Band-Gap Perovskite Solar Cells: Recent Advances and Perspectives

“…It has been reported that MAPbI 3 and MASnI 3 exhibited tetragonal I 4 cm (β phase) and pseudocubic P 4 mm (α phase) space groups, respectively. At high temperatures, MASnI 3 experienced a reversible phase structural transformation from the α phase to β phase . Such phase structural transition also occurred for MASn 1– x Pb x I 3 perovskites at room temperature.…”

“…At high temperatures, MASnI 3 experienced a reversible phase structural transformation from the α phase to β phase. 106 Such phase structural transition also occurred for MASn 1−x Pb x I 3 perovskites at room temperature. Typically, mixed Pb−Sn perovskites with low Sn concentrations (x < 0.5) displayed the same tetragonal I4cm structure as MAPbI 3 , while mixed Pb−Sn perovskites with higher Sn amounts (x > 0.5) showed the same pseudocubic P4mm structure as MASnI 3 .…”

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.…”