All‐Inorganic Cesium‐Based Hybrid Perovskites for Efficient and Stable Solar Cells and Modules

Abstract

high defect tolerance, long carrier diffusion length, and compatibility toward scalable manufacturing processes to name a few. [2][3][4][5][6][7] However, hybrid perovskites face severe degradation issues under operative conditions, which stem from the (photo) chemical instability when exposed to moisture, oxygen, UV light, and heat. [8][9][10][11][12] Among other reasons, the presence of the hydrophobic organic cation, e.g., methylammonium, can accelerate the degradation path. [12][13][14] For this reason, a greater focus has been devoted to exploring inorganic elements to replace the organic cations, for instance, using cesium to form CsPbX 3 all-inorganic perovskites. This system has been revealed of particular interest especially for the improved thermal stability of the material and, consequently, the enhanced device lifetime. [13] CsPbI 3 and CsPbBr 3 are the most studied materials within this class, with a rapid boost of their use for highly efficient solar cells, reaching 19.03% in 2019. [15] However, the PCE of CsPbX 3 -based devices are still lower than their organic-inorganic counterparts and far from the Shockley-Queisser limit calculated for their bandgap. [16] Therefore, major efforts are required to stabilize the CsPbI 3 structure and to fabricate high quality CsPbX 3 thin films, before upscaling the manufacturing toward marketable devices. In this work, we provide a compelling perspective on the most recent and innovative strategies to tackle this challenge. The structural and optoelectronic properties of CsPbX 3 materials are first sorted out, with a focus on the film morphology, crystal structure, and phase transitions of each system. Second, methods for improving the photovoltaic performances and the stability of CsPbX 3 -based devices are reported, focusing on the highest PCE and the longest device lifetimes reported up to date. Finally, we provide a perspective on the state of the art and future challenges for the upscaling of all-inorganic perovskite modules.

Stoichiometric Dissolution of Defective CsPbI2Br Surfaces for Inorganic Solar Cells with 17.5% Efficiency

“…An excitation light of 365 nm was employed for the PL study, which provided near‐surface electronic information about the perovskite with a low penetration depth of approximately 20 nm ( Figure 2 A). [ 25 ] The PL peak position, intensity, and full width at half maximum (FWHM) of all the samples are depicted in Figure 2B and the detail of in situ PL characterizations are shown in Figure 2C–E. The strongly decreased PL intensity when IPA was dropped might be attributed to the absorption or reflection of the IPA solution.…”

Black‐Yellow Bandgap Trade‐Off During Thermal Stability Tests in Low‐Temperature Eu‐Doped CsPbI3

“…To achieve this goal, some issues like the intrinsic instability of the perovskite material, especially when it is exposed to humidity and elevated temperatures, have to be fully solved. [ 5–13 ]…”

“…To achieve this goal, some issues like the intrinsic instability of the perovskite material, especially when it is exposed to humidity and elevated temperatures, have to be fully solved. [5][6][7][8][9][10][11][12][13] Recently, besides the most studied hybrid organic/inorganic perovskites (methylammonium lead iodide (MAPbI 3 ), [14] formamidinium lead iodide (FAPbI 3 ), and methylammonium MA-FA mixed perovskite), the all-inorganic Cs-based perovskites [15] like CsPbI 3 have received much attention because of their greater thermal stability. Moreover, CsPbI 3 perovskites with energy gap (E gap %1.73 eV) are promising candidates for Si/PSK monolithic tandem solar cells.…”

Strategies for highly efficient and stable cesium lead iodide perovskite photovoltaics: mechanisms and processes

“…Furthermore, it should be pointed out that the various strategies summarized above – additive engineering, dimensionality engineering, doping engineering and quantum dot engineering – are mostly limited to small-area devices (0.09 cm 2 ) prepared in inert atmospheres by the spin coating method, and it is difficult to apply them to large-area modules due to the too fast crystallization of the inorganic perovskite film. 178 Besides, the spin coating method showed a high precursor solution waste ratio of over 90%, which may negate the low-cost advantage of PSCs. 43 Therefore, finding suitable promotion strategies for large-area modules is another top priority for future development.…”