文献类型：期刊文献

英文题名：Spatially separated exciplex emission with spacer thickness- and content-tunable properties: Experimental and computational investigations

作者：Lu, Zhaoyue[1];Jiang, Wei[1];Tang, Zongkai[1];Wang, Xiao[1]

机构：[1]East China Univ Sci & Technol, Sch Phys, Shanghai 200237, Peoples R China

年份：2025

卷号：163

期号：18

外文期刊名：JOURNAL OF CHEMICAL PHYSICS

收录：;EI(收录号：20254719548100);WOS:【SCI-EXPANDED(收录号:WOS:001616278200003)】；

语种：英文

外文关键词：Blue shift - Charge transfer - Density functional theory - Design for testability - Electroluminescence - Excited states - Optoelectronic devices

摘要：The tunability of long-range charge-transfer (CT) states in spatially separated exciplex systems presents a fundamental challenge in excited-state physics. This study systematically examines how controlled donor-acceptor (D-A) separation modulates the electroluminescent properties and excited-state electronic structures of TAPC-PO-T2T exciplex systems, using mCP as a spacer introduced via interfacial layering or bulk doping. Due to weakened Coulombic interaction by extended D-A spacing, increasing mCP spacer thickness (0-6 nm) or doping concentration (0-80 wt. %) induces a systematic blue shift (Delta lambda = 35 nm for interlayer and 18 nm for doping) in exciplex emission. Through precise spacer engineering, we achieve remarkable EQE enhancements: (i) 170% improvement with an optimal 8 nm mCP interlayer and (ii) 61% increase at 80 wt. % mCP doping content. To uncover the underlying electronic origins, we construct a series of donor-spacer-acceptor (D-S-A) model systems (DnSA/DnSAS, n = 0-5) and perform density functional theory (DFT) calculations. DFT calculation results show excellent agreement with experiments, particularly in predicting the blue-shifted emission through calculated increases in TAPC -> PO-T2T CT state energy with spacer incorporation. Furthermore, more near-degenerate singlet-triplet states could promote efficient reverse intersystem crossing, explaining the enhanced electroluminescent performance. These insights collectively demonstrate that molecular spacer engineering is a powerful strategy for (i) spectral tuning via precise D-A distance control and (ii) efficiency optimization through excited-state energy alignment, offering new insights into the design of high-performance exciplex-based optoelectronic materials and devices.