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Surface Ligands Management for Efficient CsPbBrI <sub/>2</sub> Perovskite Nanocrystal Solar Cells
摘要： CsPbX3 (X= Cl, Br, I) inorganic perovskite nanocrystals (PNCs) not only maintain the excellent optical and electronic properties of bulk material but also possess the features of nano-materials, such as tunable bandgap, easily processable colloidal ink, enable them to be suitable for incorporation into various electronic devices and compatible with printing techniques. In contrast to the traditional II-VI and III-V semiconductor nanocrystals, the unique defect-tolerance effect makes the CsPbX3 PNCs very promising materials for optoelectronic applications. The ligands around the NCs play a critical role on the optoelectronic devices performance. Here, through a facile hexane/ethyl acetate (MeOAc) solvent treatment method to control the ligand amount around the CsPbBrI2 PNCs, we systematically demonstrated the impact of ligand amount on the performance of solar cell devices and first quantify the ligand amount precisely by nuclear magnetic resonance (NMR) internal standard method. Through controlling the ligand amount, the film quality, charge transfer and transport properties are largely improved. In addition, a simple annealing process is applied to improve the interface properties by partial crystal fusion. As a consequence, the photovoltaic power conversion efficiency (PCE) of 12.2% is achieved by employing a n-i-p device structure, which is the highest performance of mixed-halide CsPbX3 NCs solar cells. This work emphasizes the important role of ligand amount on the NCs device performance.
关键词： ligand amount control,CsPbBrI2,solar cell,inorganic perovskite,nanocrystals
更新于2025-09-23 15:19:57
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Red-emitting CsPbBrI2/PbSe heterojunction nanocrystals with high luminescent efficiency and stability for bright light-emitting diodes
摘要： All inorganic perovskite CsPbX3 (X = Cl, Br, I) nanocrystals (NCs) have been endowed great promise for optoelectronic device applications. However, further practical applications of these NCs are blocked because of their poor stability. In the present work, we propose a novel strategy to synthesize highly luminescent and stable red-emitting CsPbBrI2/PbSe heterojunction nanocrystals (h-NCs) via an epitaxial solution growth method, in which lattice-matching condition between CsPbBrI2 and PbSe was satisfied, and each CsPbBrI2 NC was partially covered by PbSe in the CsPbBrI2/PbSe heterodimers. The ultrafast transient absorption (TA) and time-resolved photoluminescence (TRPL) spectroscopy revealed that incorporation of PbSe can modify surface and hence passivate the surface trap states of the CsPbBrI2 NCs, helping to enhance the photoluminescence quantum yields (PLQY) (up to 83.4%) of these CsPbBrI2/PbSe h-NCs. First-principle calculations based on DFT confirmed that the significantly improved stability of these CsPbBrI2/PbSe h-NCs was attributed to the strong chemical bonding of selenium atoms of PbSe and lead atoms of PbX2-terminated surface from CsPbBrI2. Thin films of these CsPbBrI2/PbSe h-NCs can maintain bright red PL brightness and cubic phase even after 15-day storage under a high humidity condition. Benefiting from the performances of high stability and luminescent efficiency, these red-emitting CsPbBrI2/PbSe h-NCs have a positive implication for bright light-emitting diodes (LEDs).
关键词： nanocrystals,stability,heterojunction,light-emitting diodes,CsPbBrI2/PbSe
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Unraveling the Moisture-induced Decomposition Mechanism of Red-Emitting Perovskite CsPbBrI <sub/>2</sub> Nanocrystals and Enhancing their Stability through Copper(II) Substitution
摘要： The red-Emitting perovskite CsPb(BrxI1-x)3 (0<x<1) nanocrystals (NCs) is hindered because of their low structural stability, and the moisture-induced degradation pathways of these red-Emitting perovskite are not well-defined. In the present work, we show that the moisture-induced degradation of CsPbBrI2 NCs spontaneously forms CsPbBr3 (α) and CsPbI3(δ) and other decomposition products. On the other hand, highly stable and luminescent red perovskite CsPbBrI2 NCs were achieved through copper substitution and halide rich passivation strategy. We demonstrated that the incorporation of Cu2+ ions can enhance formation energy, causing a slight lattice contraction, and hence stabilize the cubic phase of these NCs. Cu2+-substituted CsPbBrI2 NCs with higher luminescence were synthesized in a halide-rich passivation method. The highly stable and luminescent Cu2+-substituted CsPbBrI2 NCs can function well as efficient light emitters toward fabrication of the high-performance red perovskite LEDs.
关键词： perovskite nanocrystals,stability,CsPbBrI2,copper-substitution,light-emitting diodes
更新于2025-09-12 10:27:22