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Modulation of Ligands Conjugation for Efficient FAPbBr3 based Green Light-Emitting Diodes
摘要： Organic ligands capped on surface of perovskite nanocrystals (PeNCs) strongly influence the optical and electrical properties of the obtained PeNCs films, which are fundamental for efficient perovskite light-emitting diodes (PeLEDs). Here, we investigate the ligands effect through introduction of ligands with strong π conjugation, 1-(1-naphthyl)ethylamine bromide (NEABr), for the fabrication of FAPbBr3 PeNCs. Compared to the widely applied ligands of phenylethylamine bromide (PEABr), NEABr molecules containing naphthalene ring possess more delocalized electrons and better conductivity, which is beneficial for charge injection and transportation between interfaces. By varying the ligands ratio, high quality three dimensional FAPbBr3 PeNCs films with photoluminescence quantum yields up to 80% are fabricated. Based on the optimized PeNCs films, electroluminescent (EL) devices achieve a maximum external quantum efficiency of 8.6%, which is about three times higher than that of EL devices based on PEABr. Importantly, through understanding into the ligands effect, we demonstrate that the enhanced device efficiency is attributed to lower defect densities and decreased interfacial resistance in NEABr derived EL devices. Our findings about ligands conjugation on device performance may benefit other perovskites based optoelectronic devices.
关键词： ligands conjugation,perovskite nanocrystals,light-emitting diodes,charge injection,FAPbBr3
更新于2025-09-16 10:30:52
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Micro tuning of wide-bandgap perovskite lattice plane for efficient and robust high-voltage planar solar cells exceeding 1.5 V
摘要： 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 micro tuning of crystal-lattice by cesium incorporation into A-site on low temperature processed formamidinium lead tribromide (CH(NH2)2PbBr3 = FAPbBr3) perovskite films. The partial incorporation of cesium bromide (CsBr) in to FAPbBr3 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 FAPbBr3 containing 8% Cs (Cs0.08FA0.92PbBr3) exhibited an optimum PCE (power conversion efficiency) of 8.56% with a Voc (open-circuit voltage) of 1.516 V, which is higher than the PCE of 7.07% and Voc of 1.428 V of the FAPbBr3 device. Photoluminescence-intensity and temporal-imaging measurements were conducted by laser scanning confocal time-resolved microscopy (LCTM), which revealed that CsBr incorporation into a FAPbBr3 film significantly suppresses the non-radiative recombination pathways and homogenizes the spatial distribution of photoluminescence. It was visualized that the incorporation of CsBr in FAPbBr3 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 Cs0.08FA0.92PbBr3 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 FAPbBr3 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 Cs0.08FA0.92PbBr3 devices were more robust than the FAPbBr3 devices.
关键词： Low-temperature process,High-photovoltage,Wide-bandgap,CsBr,FAPbBr3
更新于2025-09-12 10:27:22