Highly luminescent colloidal CdS quantum dots with efficient near-infrared electroluminescence in light-emitting diodes
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Quantum dots are of growing interest as emissive materials in light emitting devices. Here ﬁrst we report the formation of highly luminescent organic capped colloidal cadmium sulﬁde (CdS) nanoparticles having the highest photoluminescence quantum yield of 69% in solutions and 34% in neat thin ﬁlms in the near-infrared range. Second, we also show eﬃcient electroluminescence in the near-infrared from solution processed hybrid light emitting diodes (LEDs) based on such colloidal CdS quantum dots embedded in an organic semiconductor matrix forming a nanocomposite active layer. We also discuss the device structure and role of the doped active layer in eﬃciency improvement. With optimized active layer thickness and concentration of QDs, the device exhibits an external electroluminescence quantum eﬃciency of 0.62% at a peak emission wavelength of 760 nm, providing a route to solution processable ﬂexible light sources for biosensors and medicine.
Bansal , A K , Antolini , F , Zhang , S , Stroea , L , Orlotani , L , Lanzi , M , Serra , E , Allard , S , Scherf , U & Samuel , I D W 2016 , ' Highly luminescent colloidal CdS quantum dots with efficient near-infrared electroluminescence in light-emitting diodes ' Journal of Physical Chemistry C , vol 120 , no. 3 , pp. 1871-1880 . DOI: 10.1021/acs.jpcc.5b09109
Journal of Physical Chemistry C
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We acknowledge ﬁnancial support from FP7 project “Laser Induced Synthesis of Polymeric Nanocomposite Materials and Development of Micro-Patterned Hybrid Light Emitting Diodes (LED) and Transistors (LET)”-LAMP (Project G.A.247928). A.K.B. and I.D.W.S. also acknowledge ﬁnancial support from EPSRC Programme “Challenging the Limits of Photonics: Structured Light” Grant EP/J01771X/1.