posted on 2021-04-29, 15:10authored byXinyu Sui, Xiaoqing Gao, Xianxin Wu, Chun Li, Xuekang Yang, Wenna Du, Zhengping Ding, Shengye Jin, Kaifeng Wu, Tze Chien Sum, Peng Gao, Junjie Liu, Xiaoding Wei, Jun Zhang, Qing Zhang, Zhiyong Tang, Xinfeng Liu
Colloidal
CdSe nanoplatelets (NPLs) have substantial potential
in light-emitting applications because of their quantum-well-like
characteristics. The self-trapped state (STS), originating from strong
electron–phonon coupling (EPC), is promising in white light
luminance because of its broadband emission. However, achieving STS
in CdSe NPLs is extremely challenging because of their intrinsic weak
EPC nature. Herein, we developed a strong STS emission in the spectral
range of 450–600 nm by building superlattice (SL) structures
with colloidal CdSe NPLs. We demonstrated that STS is generated via
strong coupling of excitons and zone-folded longitudinal acoustic
phonons with formation time of ∼450 fs and localization length
of ∼0.56 nm. The Huang–Rhys factor, describing the EPC
strength in SL structure, is estimated to be ∼19.9, which is
much larger than that (∼0.1) of monodispersed CdSe NPLs. Our
results provide an in-depth understanding of STS and a platform for
generating and manipulating STS by designing SL structures.