Residual Nanoscale Strain in Cesium Lead Bromide Perovskite Reduces Stability and Shifts Local Luminescence

Abstract

Using nanoprobe X-ray diffraction microscopy, we investigate the relationship between residual strains from crystal growth in CsPbBr3 thin film crystals, their stability, and local bandgap. We find that out-of-plane compressive strain that arises from cooldown from crystallization is detrimental to material stability under X-ray irradiation. We also find that the optical photoluminescence red shifts as a result of the out-of-plane compressive strain. The sensitivity of bandgap to strain suggests possible applications such as stress-sensitive sensors.Mosaicity, the formation of small misorientations in neighboring crystalline domains we observe in some CsPbBr3 single crystals, indicates the significant variations in crystal quality that can occur even in single-crystal halide perovskites. The nano-diffraction results suggest that reducing local strains is a necessary path to enhance the stability of perovskite optoelectronic materials and devices from light-emitting diodes to high-energy detectors.

Anisotropic In Situ Strain‐Engineered Halide Perovskites for High Mechanical Flexibility

“…The estimation procedure of the parameters is available in Section X of the Supporting Information. [ 31–33 ] The results are shown in Figure 2c, where the corresponding values are plotted against the in situ strain ε i (with the values in Table S5, Supporting Information). All the σ str , Γ , and K IC values were largely dependent on the in situ strain by demonstrating improved values for the compressively strained films.…”

Four-Fold Multi-Modal X-ray Microscopy Measurements of a Cu(In,Ga)Se2 Solar Cell

“…So far, scanning hard X-ray microscopy of solar cells has been used predominantly for the correlation of the elemental distribution with the electrical performance [ 12 , 13 , 14 ]. Only recently, measurements of the intra-grain strain have been included [ 15 , 16 , 17 ].…”

Perspectives of Open-Air Processing to Enable Perovskite Solar Cell Manufacturing

“…The role of mechanical properties has been largely overlooked until recently. Perovskites have been identified as a mechanically fragile PV technology (Rolston et al, 2016), and several recent reports have explored strain engineering as a concept to improve optoelectronic properties (Zhu et al, 2019;Chen et al, 2020b;Kim et al, 2020) and reduce perovskite degradation (Zheng et al, 2016;Xiao et al, 2017;Zhao et al, 2017;Rolston et al, 2018;Li et al, 2019). The prospects of this effort are impactful since typical thermal processing generates large residual tensile perovskites film strain from the CTE mismatch compared to the typically stiff substrates used (i.e.…”