Low-threshold anisotropic polychromatic emission from monodisperse quantum dots  

作　　者：Yangzhi Tan Wai Yuen Fu Hemin Lin Dan Wu Xiao Wei Sun Hoi Wai Choi Kai Wang 

机构地区：[1]Institute of Nanoscience and Applications,Department of Electrical and Electronic Engineering,Southern University of Science and Technology,Shenzhen 518055,China [2]Department of Electrical and Electronic Engineering,The University of Hong Kong,Hong Kong 999077,China [3]College of New Materials and New Energies,Shenzhen Technology University,Shenzhen 518118,China

出　　处：《National Science Review》2025年第2期12-22,共11页国家科学评论(英文版)

基　　金：supported by the National Key Research and Development Program of China(2022YFB3606504);the National Natural Science Foundation of China(62122034);the Shenzhen Basic Research General Program(JCYJ20210324104413036);the Guangdong Basic and Applied Basic Research Foundation(2022A1515011071);the Shenzhen Stable Support Research Foundation(20220717215521001);the Natural Science Foun-dation of Top Talent of Shenzhen Technology University(SZTU)(GDRC202110);High Level of Special Funds(G030230001 and G03034K002)from Southern University of Science and Technology.

摘　　要：Colloidal quantum dots(QDs)are solution-processable semiconductor nanocrystals with favorable optoelectronic characteristics,one of which is their multi-excitonic behavior that enables broadband polychromatic light generation and amplification from monodisperse QDs.However,the practicality of this has been limited by the difficulty in achieving spatial separation and patterning of different colors as well as the high pumping intensity required to excite the multi-excitonic states.Here,we have addressed these issues by integrating monodisperse QDs in multi-excitonic states into a specially designed cavity,in which the QDs exhibit an anisotropic polychromatic emission(APE)characteristic that allows for tuning the emission from green to red by shifting the observation direction from perpendicular to lateral.Subsequently,the APE threshold under 300-ps pulsed excitation has been reduced from 32 to 21μJ cm^(-2)by optimizing the cavity structure.Based on the manipulation of multi-excitonic emission and angle-dependent wavelength selectivity of the developed cavity,we have fabricated a full-color micro-pixel array with a pixel size as small as 23μm by combining cavity-integrated monodisperse QDs and blue backlight.Furthermore,the threshold of APE under quasi-continuous-wave pumping was as low as 5 W cm^(-2),indicating its compatibility with commercial LEDs and/or laser diodes.Since APE arises from the multi-excitonic behavior of QDs that supports optical gain,its unprecedentedly low threshold suggests the feasibility of the diode-pumped colloidal QD laser.This work demonstrates a novel method of manipulating the QDs’optical properties beyond controlling their size,composition or structure,and reveals great potential for achieving full-color emission using monodisperse QDs.

关 键 词：colloidal quantum dots multi-excitonic emission MICROCAVITY 

分 类 号：TN2[电子电信—物理电子学]