Microtuning of the Wide-Bandgap Perovskite Lattice Plane for Efficient and Robust High-Voltage Planar Solar Cells Exceeding 1.5 V

Abstract

Iodide-free tribromide-based perovskites, with their wide bandgap of over 2.0 eV, are highly regarded as potential candidates for a photoelectrochemical water splitting system and the topmost cell in tandem solar cell. Herein, we report on the importance of microtuning of the crystal lattice by cesium incorporation into the A-site on low temperature processed formamidinium lead tribromide (CH(NH 2 ) 2 PbBr 3 = FAPbBr 3 ) perovskite films. The partial incorporation of cesium bromide (CsBr) into the FAPbBr 3 film tunes crystal-lattice interactions, resulting in a high-purity cubic crystal system with preferred orientation. An entirely low temperature processed planar photovoltaic device assembled with FAPbBr 3 containing 8% Cs (Cs 0.08 FA 0.92 PbBr 3 ) exhibited an optimum PCE (power conversion efficiency) of 8.56% with a V oc (open-circuit voltage) of 1.516 V, which is higher than the PCE of 7.07% and V oc of 1.428 V of the FAPbBr 3 device. Photoluminescenceintensity and temporal-imaging measurements were conducted by laser scanning confocal time-resolved microscopy (LCTM), which revealed that CsBr incorporation into a FAPbBr 3 film significantly suppresses the nonradiative recombination pathways and homogenizes the spatial distribution of photoluminescence. It was visualized that the incorporation of CsBr in FAPbBr 3 directly affects the bulk defect and photoluminescence properties, which provides evidence that Cs ions surely alleviate the segregation and aggregation of ions in the perovskite film. Notably, the Cs 0.08 FA 0.92 PbBr 3 film, with a carrier lifetime of about 270 ns, exhibited a 1.37-fold longer radiative recombination time than that (210 ns) observed for the FAPbBr 3 film. Furthermore, aging experiments without encapsulation under ambient (in air for 2000 h) and severe (65 °C and 65% RH for 500 h) conditions revealed that the Cs 0.08 FA 0.92 PbBr 3 devices were more robust than the FAPbBr 3 devices.

Recent Progress in Interconnection Layer for Hybrid Photovoltaic Tandems

“…b) External quantum efficiency (EQE) spectra of variable‐composition perovskite and Si solar cells reported in refs. [ 37,142,195–202 ] . c,d) Schematic illustrations of a monolithic 2‐T tandem (c) and a mechanically stacked 4‐T tandem (d).…”

Crystallization Control and Defect Passivation via a Cross-Linking Additive for High-Performance FAPbBr3 Perovskite Solar Cells

“…The partial incorporation of cesium bromide (CsBr) into the FAPbBr 3 film tunes crystal−lattice interactions, resulting in a high-purity cubic crystal system with preferred orientation. 24 Zhang et al introduced a molecule of urea and eventually a PCE of 10.61% and V OC of 1.56 V achieved with planar structured solar cells. 25 The research studies of iodide-based perovskite solar cells have shown that the defect of grain boundary in perovskite films is detrimental to charge transport and will induce energy loss.…”

“…Using sputtered ZnO as an electron transport layer can deposit quality inorganic material on top of the perovskite absorber, thereby obtaining stable p–i–n FAPbBr 3 devices with improved efficiency . Second, the grow process of the perovskite grain film has currently been regulated. − A high-quality perovskite film is propitious to the charge transport and reducing the recombination. The partial incorporation of cesium bromide (CsBr) into the FAPbBr 3 film tunes crystal–lattice interactions, resulting in a high-purity cubic crystal system with preferred orientation .…”

“…Second, the grow process of the perovskite grain film has currently been regulated. − A high-quality perovskite film is propitious to the charge transport and reducing the recombination. The partial incorporation of cesium bromide (CsBr) into the FAPbBr 3 film tunes crystal–lattice interactions, resulting in a high-purity cubic crystal system with preferred orientation . Zhang et al introduced a molecule of urea and eventually a PCE of 10.61% and V OC of 1.56 V achieved with planar structured solar cells .…”

Self‐Aggregation‐Controlled Rapid Chemical Bath Deposition of SnO2 Layers and Stable Dark Depolarization Process for Highly Efficient Planar Perovskite Solar Cells

“…Hence, other studies have focused on understanding the correlations between ion migration and these intrinsic properties. [11][12][13][14] In contrast, another set of studies found that TiO 2 , the most commonly used electron-selective layer (ESL), contributes to the occurrence of J-V hysteresis in PSCs, possibly because of its low electron mobility, chemical reactivity with the perovskite layer, and interfacial defect states. [15][16][17][18] Interesting points are the dependence of hysteresis on the contact materials and the influence of interfacial materials on ion migration.…”