Mandal Arnab, Roy Samrat, Mondal Anamika, Gupta Shresth, Pal Bipul, Bhattacharyya Sayan
Department of Chemical Sciences and Centre for Advanced Functional Materials, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur 741246, India.
Department of Physical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur 741246, India.
J Phys Chem Lett. 2022 Oct 6;13(39):9103-9113. doi: 10.1021/acs.jpclett.2c02500. Epub 2022 Sep 26.
Semiconductor nanostructures with near-unity photoluminescence quantum yields (PLQYs) are imperative for light-emitting diodes and display devices. A PLQY of 99.7 ± 0.3% has been obtained by stabilizing 91% Sn in the Dion-Jacobson (8N8)SnBr (8N8-DJ) perovskite with 1,8-diaminooctane (8N8) spacer. The PLQY is favored by a longer spacer molecule and out-of-plane octahedral tilting. The PLQY shows one-month ambient stability under high relative humidity (RH) and temperature. With -octylamine (8N) spacer, Ruddlesden-Popper (8N)SnBr (8N-RP) also shows PLQY of 91.7 ± 0.6%, but it has poor ambient stability. The 5-300 K PL experiments decipher the self-trapped excitons (STEs) where the self-trapping depth is 25.6 ± 0.4 meV below the conduction band because of strong carrier-phonon coupling. The microsecond long-lived STE dominates over the band edge (BE) peaks at lower excitation wavelengths and higher temperatures. The higher PLQY and stability of 8N8-DJ are due to the stronger interaction between SnBr octahedra and 8N8 spacer, leading to a rigid structure.
具有近乎单位光致发光量子产率（PLQYs）的半导体纳米结构对于发光二极管和显示设备至关重要。通过用1,8 - 二氨基辛烷（8N8）间隔基稳定狄翁 - 雅各布森（8N8）SnBr（8N8 - DJ）钙钛矿中91%的Sn，获得了99.7±0.3%的PLQY。较长的间隔分子和面外八面体倾斜有利于PLQY。在高相对湿度（RH）和温度下，PLQY显示出一个月的环境稳定性。对于具有 - 辛胺（8N）间隔基的Ruddlesden - Popper（8N）SnBr（8N - RP），其PLQY也为91.7±0.6%，但环境稳定性较差。5 - 300 K的PL实验揭示了自陷激子（STE），由于强载流子 - 声子耦合，自陷深度在导带以下25.6±0.4 meV。在较低激发波长和较高温度下，微秒级长寿命的STE在带边（BE）峰中占主导。8N8 - DJ较高的PLQY和稳定性归因于SnBr八面体与8N8间隔基之间更强的相互作用，从而形成刚性结构。
