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Efficient Quantum Dot Light‐Emitting Diodes Based on Well‐Type Thick‐Shell Cd x Zn 1− x S/CdSe/Cd y Zn 1− y S Quantum Dots
Author(s) -
Bai Jinke,
Wang Linfeng,
Chen Wenyong,
Jin Xiao,
Li Qinghua,
Wang Yuxiao,
Zhang Xueru,
Song Yinglin
Publication year - 2020
Publication title -
particle and particle systems characterization
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 56
eISSN - 1521-4117
pISSN - 0934-0866
DOI - 10.1002/ppsc.202000115
Subject(s) - quantum dot , ternary operation , diode , materials science , photoluminescence , optoelectronics , light emitting diode , quenching (fluorescence) , lattice (music) , fluorescence , physics , optics , computer science , programming language , acoustics
Device grade quantum dots (QDs) require QDs ensembles to retain their original superior optical properties as in solution. QDs with thick shells are proven effective in suppressing the inter‐dot interaction and preserving the emission properties for QDs solids. However, lattice strain–induced defects may form as the shell grows thicker, resulting in a notable photoluminescence quenching. Herein, a well‐type Cd x Zn 1− x S/CdSe/Cd y Zn 1− y S QDs is proposed, where ternary alloys CdZnS are adopted to match the lattice parameter of intermediate CdSe by separately adjusting the x and y parameters. The resultant thick‐shell Cd 0.5 Zn 0.5 S/CdSe/Cd 0.73 Zn 0.27 S QDs reveal nonblinking properties with a high PL QY of 99% in solution and 87% in film. The optimized quantum dot light‐emitting diodes (QLEDs) exhibit a luminance of 31547.5 cd m −2 at the external quantum efficiency maximum of 21.2% under a bias of 4.0 V. The shell thickness shows great impact on the degradation of the devices. The T 50 lifetime of the QLEDs with 11.2 nm QDs reaches 251 493 h, which is much higher than that of 6.5 and 8.4 nm QDs counterparts. The performances of the well‐type thick‐shell QLEDs are comparable to state‐of‐the‐art devices, suggesting that this type of QDs is a promising candidate for efficient optoelectronic devices.