Kim Geon Yeong, Kim Shinho, Choi Jinyoung, Kim Moohyun, Lim Hunhee, Nam Tae Won, Choi Wonseok, Cho Eugene N, Han Hyeuk Jin, Lee ChulHee, Kim Jong Chan, Jeong Hu Young, Choi Sung-Yool, Jang Min Seok, Jeon Duk Young, Jung Yeon Sik
Department of Materials Science and Engineering , Korea Advanced Institute of Science and Technology (KAIST) , 291 Daehak-ro , Yuseong-gu , Daejeon 34141 , Republic of Korea.
School of Electrical Engineering , Korea Advanced Institute of Science and Technology (KAIST) , 291 Daehak-ro , Yuseong-gu , Daejeon 34141 , Republic of Korea.
Nano Lett. 2019 Oct 9;19(10):6827-6838. doi: 10.1021/acs.nanolett.9b01941. Epub 2019 Sep 6.
Achieving high emission efficiency in solid-state quantum dots (QDs) is an essential requirement for high-performance QD optoelectronics. However, most QD films suffer from insufficient excitation and light extraction efficiencies, along with nonradiative energy transfer between closely adjacent QDs. Herein, we suggest a highly effective strategy to enhance the photoluminescence (PL) of QD composite films through an assembly of QDs and poly(styrene--4-vinylpyridine)) (PS--P4VP) block copolymer (BCP). A BCP matrix casted under controlled humidity provides multiscale phase-separation features based on (1) submicrometer-scale spinodal decomposition between polymer-rich and water-rich phases and (2) sub-10 nm-scale microphase separation between polymer blocks. The BCP-QD composite containing bicontinuous random pores achieves significant enhancement of both light absorption and extraction efficiencies via effective random light scattering. Moreover, the microphase-separated morphology substantially reduces the Förster resonance energy transfer efficiency from 53% (pure QD film) to 22% (BCP-QD composite), collectively achieving an unprecedented 21-fold enhanced PL over a broad spectral range.
在固态量子点（QD）中实现高发射效率是高性能量子点光电器件的基本要求。然而，大多数量子点薄膜存在激发效率和光提取效率不足的问题，以及相邻量子点之间的非辐射能量转移。在此，我们提出一种高效策略，通过量子点与聚（苯乙烯 - 4 - 乙烯基吡啶）（PS - P4VP）嵌段共聚物（BCP）的组装来增强量子点复合薄膜的光致发光（PL）。在受控湿度下浇铸的BCP基质基于（1）富含聚合物相和富含水相之间的亚微米级旋节线分解以及（2）聚合物嵌段之间小于10纳米级的微相分离提供多尺度相分离特征。含有双连续随机孔的BCP - QD复合材料通过有效的随机光散射实现了光吸收和提取效率的显著提高。此外，微相分离形态将Förster共振能量转移效率从53%（纯量子点薄膜）大幅降低至22%（BCP - QD复合材料），共同在宽光谱范围内实现了前所未有的21倍PL增强。
