Aggregation-free Sensitizer Dispersion in Rigid Ionic Crystals for Efficient Solid-State Photon Upconversion and Demonstration of Defect Effects
Aggregation-free Sensitizer Dispersion in Rigid Ionic Crystals for Efficient Solid-State Photon Upconversion and Demonstration of Defect Effects
复制标题
刚性离子晶体中的无聚集敏化剂分散，用于高效固态光子上转换和缺陷效应演示
DOI：
10.1039/c8tc00977e
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
and Nobuo Kimizuka
中科院分区：
文献类型：
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作者：
Taku Ogawa;Nobuhiro Yanai;Saiya Fujiwara;Thus-Quyen Thai Nguyen;and Nobuo Kimizuka
基于三重态-三重态湮灭（TTA-UC）的固态光子上转换由于其规避光电电池中亚带隙光子损失的潜力而引起了人们的广泛关注。固体晶体中TTA-UC有两个长期存在的重要问题。为什么晶体系统的UC效率通常很低？构建高效上转换晶体的合理策略是什么？在这项工作中，通过采用一个简单的模型系统来解决这些问题，其中离子相互作用起关键作用。当蒽基离子受体（发射器）晶体在阴离子供体（敏化剂）分子存在下生长时，供体分子被自发地吸收并均匀地分散在受体晶体中而不聚集。高效UC是由于定量三重态能量转移（TET）从纳入供体到周围受体的结果。研究发现，机械磨削供体掺杂单晶导致UC效率显著降低，表明晶体中形成的陷阱位点对UC性能有显著的负面影响。从当前离子晶体体系中获得的重要基础知识为开发高效的固态ta - uc体系提供了合理的设计指导。
Solid-state photon upconversion based on triplet–triplet annihilation (TTA-UC) has attracted much interest because of its potential to circumvent the loss of sub-bandgap photons in photovoltaic cells. There are two important long-standing questions for TTA-UC in solid crystals. Why is the UC efficiency often low in crystalline systems? What is the rational strategy to construct efficient upconverting crystals? In this work, these issues are addressed by employing a simple model system where ionic interactions play a key role. When crystals of an anthracene-based ionic acceptor (emitter) are grown in the presence of anionic donor (sensitizer) molecules, the donor molecules are spontaneously taken up and dispersed homogeneously in acceptor crystals without aggregation. Highly efficient UC is achieved as a consequence of quantitative triplet energy transfer (TET) from the incorporated donor to the surrounding acceptor. It is found that the mechanical grinding of the donor-doped single crystals leads to a significant decrease in UC efficiency, suggesting that trap sites formed in the crystals have a significant negative impact on the UC performance. The important fundamental knowledge obtained from the current ionic crystal system offers rational design guidelines towards the development of efficient TTA-UC systems in the solid-state.