Quantum Dot Self-Assembly Enables Low-Threshold Lasing

Chun Zhou, Joao M. Pina, Tong Zhu, Darshan H. Parmar, Hao Chang, Jie Yu, Fanglong Yuan, Golam Bappi, Yi Hou, Xiaopeng Zheng, Jehad Abed, Hao Chen, Jian Zhang, Yuan Gao, Bin Chen, Ya-Kun Wang, Haijie Chen, Tianju Zhang, Sjoerd Hoogland, Makhsud I. SaidaminovLiaoxin Sun, Osman Bakr, Hongxing Dong, Long Zhang, E. Sargent

Research output: Contribution to journalArticlepeer-review

Abstract

Perovskite quantum dots (QDs) are of interest for solution-processed lasers; however, their short Auger lifetime has limited lasing operation principally to the femtosecond temporal regime the photoexcitation levels to achieve optical gain threshold are up to two orders of magnitude higher in the nanosecond regime than in the femtosecond. Here the authors report QD superlattices in which the gain medium facilitates excitonic delocalization to decrease Auger recombination and in which the macroscopic dimensions of the structures provide the optical feedback required for lasing. The authors develope a self-assembly strategy that relies on sodiumd-an assembly director that passivates the surface of the QDs and induces self-assembly to form ordered three-dimensional cubic structures. A density functional theory model that accounts for the attraction forces between QDs allows to explain self-assembly and superlattice formation. Compared to conventional organic-ligand-passivated QDs, sodium enables higher attractive forces, ultimately leading to the formation of micron-length scale structures and the optical faceting required for feedback. Simultaneously, the decreased inter-dot distance enabled by the new ligand enhances exciton delocalization among QDs, as demonstrated by the dynamically red-shifted photoluminescence. These structures function as the lasing cavity and the gain medium, enabling nanosecond-sustained lasing with a threshold of 25 µJ cm-2 .
Original languageEnglish (US)
Pages (from-to)2101125
JournalAdvanced Science
DOIs
StatePublished - Aug 27 2021

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