Doublet luminescence due to coexistence of excitons and electron-hole plasmas in optically excited CH3NH3PbBr3 single crystal |
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| Affiliation: | 1.School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China;2.School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 610054, China |
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| Abstract: | Doublet luminescence from hybrid metal trihalide perovskite semiconductors is observed along with materials processing when high-quality single crystals are obtainable. Yet, the underlying physical mechanism remains poorly understood. Here, we report controllable solution-processed crystallization that affords high-quality CH3NH3PbBr3 single crystals with atomically flat pristine surfaces. Front-face photoluminescence (PL) shows doublet luminescence components with variable relative intensities depending on the crystal surface conditions. We further find that the low-energy PL component with asymmetric spectral line-shape becomes predominant when the atomically flat crystal surfaces are passivated in the ion-abundant saturated solutions, while poor-quality single crystal with visually rough surface only gives the high-energy PL with symmetric line-shape. The asymmetric spectral line-shape of the low-energy PL matches perfectly with the simulated bandedge emission. Therefore, the low-energy PL component is attributable to the intrinsic bandedge emission from the crystal bulk while the high-energy one to surface-specific emission. Elliott fitting to the absorption data and multi-exponential fitting to the time-resolved photoluminescence traces jointly indicate the coexistence of excitons and electron-hole plasmas in optically excited CH3NH3PbBr3 single crystals, thereby catching the physical merit that leads to the occurrence of doublet luminescence. |
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| Keywords: | semiconductor crystal surface luminescence |
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