Open AccessQuantum Dot Self‐Assembly Enables Low‐Threshold Lasing
Author(s) -
Zhou Chun,
M. Pina Joao,
Zhu Tong,
H. Parmar Darshan,
Chang Hao,
Yu Jie,
Yuan Fanglong,
Bappi Golam,
Hou Yi,
Zheng Xiaopeng,
Abed Jehad,
Chen Hao,
Zhang Jian,
Gao Yuan,
Chen Bin,
Wang YaKun,
Chen Haijie,
Zhang Tianju,
Hoogland Sjoerd,
Saidaminov Makhsud I.,
Sun Liaoxin,
Bakr Osman M.,
Dong Hongxing,
Zhang Long,
H. Sargent Edward
Publication year - 2021
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.202101125
Subject(s) - lasing threshold , quantum dot , materials science , delocalized electron , femtosecond , nanosecond , optoelectronics , auger effect , photoexcitation , photoluminescence , exciton , laser , nanotechnology , physics , optics , condensed matter physics , atomic physics , auger , excited state , wavelength , quantum mechanics
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 .