Abstract

We report on the synthesis of highly fluorescent red-emitting InP quantum dots (QDs) and their application to the fabrication of a high-efficiency QD-light-emitting diode (QLED). The core/shell heterostructure of the QDs is elaborately tailored toward a multishelled structure with a composition-gradient ZnSeS intermediate shell and an outer ZnS shell. Using the resulting InP/ZnSeS/ZnS QDs as an emitting layer, all-solution-processible red InP QLEDs are fabricated with a hybrid multilayered device structure having an organic hole transport layer (HTL) and an inorganic ZnO nanoparticle electron transport layer. Two HTLs of poly(9-vinlycarbazole) or $\text{poly}[(9,9\text{-}\text{dioctylfluorenyl}\text{-}2,7\text{-}\text{diyl})\text{-}\mathrm{co}\text{-}(4,4^{\prime }\text{-}(N\text{-}(4\text{-}\sec \text{-}\text{butylphenyl}))\text{diphenyl}\text{-}\text{amine})$, whose hole mobilities are different by at least three orders of magnitude, are individually applied for QLED fabrication and such HTL-dependent device performances are compared. Our best red device displays exceptional figures of merit such as a maximum luminance of $2849\mathrm{cd}/{\mathrm{m}}^2$, a current efficiency of $4.2\mathrm{cd}/\mathrm{A}$, and an external quantum efficiency of 2.5%.

© 2016 Optical Society of America

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