posted on 2023-08-23, 14:17authored byXiao Liang, Emek G. Durmusoglu, Maria Lunina, Pedro Ludwig Hernandez-Martinez, Vytautas Valuckas, Fei Yan, Yulia Lekina, Vijay Kumar Sharma, Tingting Yin, Son Tung Ha, Ze Xiang Shen, Handong Sun, Arseniy Kuznetsov, Hilmi Volkan Demir
The strength of electrostatic interactions (EIs) between
electrons
and holes within semiconductor nanocrystals profoundly affects the
performance of their optoelectronic systems, and different optoelectronic
devices demand distinct EI strength of the active medium. However,
achieving a broad range and fine-tuning of the EI strength for specific
optoelectronic applications is a daunting challenge, especially in
quasi two-dimensional core–shell semiconductor nanoplatelets
(NPLs), as the epitaxial growth of the inorganic shell along the direction
of the thickness that solely contributes to the quantum confined effect
significantly undermines the strength of the EI. Herein we propose
and demonstrate a doubly gradient (DG) core–shell architecture
of semiconductor NPLs for on-demand tailoring of the EI strength by
controlling the localized exciton concentration via in-plane architectural
modulation, demonstrated by a wide tuning of radiative recombination
rate and exciton binding energy. Moreover, these exciton-concentration-engineered
DG NPLs also exhibit a near-unity quantum yield, high photo- and thermal
stability, and considerably suppressed self-absorption. As proof-of-concept
demonstrations, highly efficient color converters and high-performance
light-emitting diodes (external quantum efficiency: 16.9%, maximum
luminance: 43,000 cd/m2) have been achieved based on the
DG NPLs. This work thus provides insights into the development of
high-performance colloidal optoelectronic device applications.