Grain size control in quasi-two-dimensional perovskite thin film via intermediate phase engineering for efficient bound exciton generation  

采用中间态设计控制准二维钙钛矿薄膜晶粒尺寸实现高效束缚激子的产生

作　　者：Guohui Li Wenhui Zhao Kai Lin Kefan Zhao Yujing Wang Aohua Niu Rong Weng Kaibo Zheng Yanxia Cui 李国辉;赵文慧;林凯;赵柯帆;王育景;牛澳华;温荣;郑凯波;崔艳霞

机构地区：[1]College of Electronic Information and Optical Engineering,Key Laboratory of Interface Science and Engineering in Advanced Materials,Key Lab of Advanced Transducers and Intelligent Control System of Ministry of Education,Taiyuan University of Technology,Taiyuan 030024,China [2]Chemical Physics Division and NanoLund,Lund University,Box 124,22100,Lund,Sweden

出　　处：《Science China Materials》2024年第12期3925-3931,共7页中国科学（材料科学）（英文版）

基　　金：supported by the National Natural Science Foundation of China(U21A20496 and 12104334);the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(20230011);the Research Program Supported by ShanxiZheda Institute of Advanced Materials and Chemical Engineering(2022SXTD020);the Central Government Guides Local Funds for Scientific and Technological Development(YDZJSX20231A010);the Natural Science Foundation of Shanxi Province(202203021222102);the State Key Laboratory Program of Quantum Optics and Quantum Optics Devices(KF202306);the support from a research grant(VIL50350)from VILLUM FONDEN,Denmark,the Swedish Research Council(2021-05319);the Swedish foundation of international cooperation in research and higher education(CH2019-8248)。

摘　　要：Quasi-two dimensional(2D)perovskites have emerged as a promising class of materials due to their remarkable photoluminescence efficiency,which stems from their exceptionally high exciton binding energies.The spatial confinement of excitons within smaller grain sizes could enhance the formation of biexcitons leading to higher radiative recombination efficiency.However,the synthesis of high-quality quasi-2D perovskite thin films with controllable grain sizes remains a challenging task.In this study,we present a facile method for achieving quasi-2D perovskite thin films with controllable grain sizes ranging from 500 to 900 nm.This is accomplished by intermediate phase engineering during the film fabrication process.Our results demonstrate that quasi-2D perovskite films with smaller grain sizes exhibit more efficient bound exciton generation and a reduced stimulated emission threshold down to 15.89µJ cm^(−2).Furthermore,femtosecond transient absorption measurements reveal that the decay time of bound excitons is shorter in quasi-2D perovskites with smaller grain sizes compared to that of those with larger grains at the same pump density,which is 230.5 ps.This observation suggests a more efficient exciton recombination process in the smaller grain size regime.Our findings would offer a promising approach for the development of efficient bound exciton lasers.准二维钙钛矿因其高激子结合能而具有优异的光致发光效率,已成为一种极具前景的新型材料.将激子束缚在更小尺寸的晶粒中可以促进双激子的形成,并提高辐射复合效率.然而,合成具有可控晶粒尺寸的高品质准二维钙钛矿薄膜仍然面临挑战.本研究通过在薄膜制备过程中进行中间相设计来实现晶粒尺寸从500至900 nm可控的准二维钙钛矿薄膜的制备.结果表明,具有更小晶粒的准二维钙钛矿能更高效地产生束缚激子,并具有低至15.89µJ cm^(−2)的受激辐射阈值.此外,飞秒瞬态吸收光谱显示在相同的泵浦能量密度下,束缚激子的衰减时间在具有更小晶粒的二维钙钛矿中更短,约为230.5 ps.证实了更小的晶粒使二维钙钛矿具有更高效的激子复合过程.本研究结果有望用于开发高效束缚激子激光.

关 键 词：quasi-2D perovskite intermediate phase engineering bound exciton generation grain size control 

分 类 号：TB383.2[一般工业技术—材料科学与工程]