School of Chemistry and Chemical Engineering, Shandong University , Jinan 250100, China.
J Am Chem Soc. 2017 Jun 28;139(25):8772-8776. doi: 10.1021/jacs.7b05073. Epub 2017 Jun 19.
The redox nature and electrochemiluminescence (ECL) of highly crystallized organometal halide perovskite CHNHPbBr nanocrystals (NCs) in aqueous medium were investigated for the first time. CHNHPbBr NCs could be electrochemically reduced to negative charge states by injecting electrons into the lowest unoccupied molecular orbitals and oxidized to positive charge states by removing electrons from the highest occupied molecular orbitals; charge transfer between NCs with positive and negative charge states could produce ECL. The redox sequence of CHNHPbBr NCs played an important role in the generation of charge-transfer-mediated ECL; transient ECL could be achieved only by electrochemically reducing positive-charged NCs in an annihilation route. A large redox current was unfavorable for ECL. Charge mobility within CHNHPbBr NCs had an important effect on ECL intensity in a co-reactant route, which is promising for photovoltaic and optoelectronic device applications. Importantly, the ECL spectra of CHNHPbBr NCs were almost identical to their photoluminescence spectra, with a maximum emission around 535 nm and full width at half-maximum around 25 nm; this might open a way to obtaining monochromatic ECL using highly crystallized NCs as emitters, which makes them promising for use in color-selective ECL analysis.
首次研究了高度结晶的有机金属卤化物钙钛矿 CHNHPbBr 纳米晶体（NCs）在水介质中的氧化还原性质和电致化学发光（ECL）。CHNHPbBr NCs 可以通过向最低未占据分子轨道注入电子而被电化学还原为负电荷状态，也可以通过从最高占据分子轨道中除去电子而被氧化为正电荷状态；正电荷和负电荷状态的 NCs 之间的电荷转移可以产生 ECL。CHNHPbBr NCs 的氧化还原顺序在产生电荷转移介导的 ECL 中起着重要作用；只有通过电化学还原正电荷 NCs 以消除途径才能实现瞬态 ECL。大的氧化还原电流不利于 ECL。CHNHPbBr NCs 内的电荷迁移对共反应物途径中的 ECL 强度有重要影响，这对光伏和光电设备应用有很大的前景。重要的是，CHNHPbBr NCs 的 ECL 光谱与它们的光致发光光谱几乎相同，最大发射约为 535nm，半峰全宽约为 25nm；这可能为使用高度结晶的 NCs 作为发射器获得单色 ECL 开辟了一条途径，这使得它们在颜色选择的 ECL 分析中很有前景。
