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. 2016 Jan 29:6:19991.
doi: 10.1038/srep19991.

A Facile and Low-Cost Method to Enhance the Internal Quantum Yield and External Light-Extraction Efficiency for Flexible Light-Emitting Carbon-Dot Films

Z C Jiang  1 , T N Lin  1 , H T Lin  1 , M J Talite  1 , T T Tzeng  1 , C L Hsu  1 , K P Chiu  1 , C A J Lin  2 , J L Shen  1 , C T Yuan  1
Affiliations

A Facile and Low-Cost Method to Enhance the Internal Quantum Yield and External Light-Extraction Efficiency for Flexible Light-Emitting Carbon-Dot Films

Z C Jiang et al. Sci Rep. .

Abstract

Solution-processed, non-toxic carbon dots (CDs) have attracted much attention due to their unique photoluminescence (PL) properties. They are promising emissive layers for flexible light-emitting devices. To this end, the CDs in pristine aqueous solutions need to be transferred to form solid-state thin films without sacrificing their original PL characteristics. Unfortunately, solid-state PL quenching induced by extra non-radiative (NR) energy transfer among CDs would significantly hinder their practical applications in optoelectronics. Here, a facile, low-cost and effective method has been utilized to fabricate high-performance CD/polymer light-emitting flexible films with submicron-structured patterns. The patterned polymers can serve as a solid matrix to disperse and passivate CDs, thus achieving high internal quantum yields of 61%. In addition, they can act as an out-coupler to mitigate the waveguide-mode losses, approximately doubling the external light-extraction efficiency. Such CD/polymer composites also exhibit good photo-stability, and thus can be used as eco-friendly, low-cost phosphors for solid-state lighting.

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Conflict of interest statement

The authors declare no competing financial interests.

Figures

Figure 1
Figure 1. PL spectra for CDs dispersed in an aqueous solution and embedded into PVA matrices along with a photograph showing luminescent CDs in solution under UV irradiation.
Figure 2
Figure 2. Schematic illustration of PL emission from CDs with multiple non-radiative decay rates.
Figure 3
Figure 3. Time-resolved PL decay curves for liquid CDs and solid CD/PVA composites together with the fitting results for solid composites in the inset.
Figure 4
Figure 4. PL spectra for solid CD/polymer composites with and without the patterns of the grating structures along with an AFM imaging of the grating patterns in the inset.
Figure 5
Figure 5
(a) Time-resolved PL decay profiles for solid CD/PVA composites at room temperature and 400 K and (b) the PL intensity as a function of observation time for solid composites at room temperature and 400 K.
See this image and copyright information in PMC

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