Excellent color rendering index single system white light emitting carbon dots for next generation lighting devices

Recently, quantum dots (QDs) are finding enormous application in white light emitting diodes (WLEDs) and WLEDs with high color rendition are in high demand. QD-WLEDs use different color (Red, Blue, Green) emitting QDs to obtain white light. Use of different color emitting QDs affect purity of white light due to self-absorption losses and QD degradation, in the long run affecting color rendering index (CRI) of WLEDs. Herein, we report low cost, environment friendly, open air atmosphere synthesis of single system white light emitting carbon dots (CDs) with broad emission bandwidth ranging 116 -143 nm and quantum yields (QY) similar to 5 - 13 % in colloidal state by modifying CD surface. Furthermore, carbon dot polymer phosphor (CD-PDMS phosphor) is fabricated which emits white light under UV illumination with a record emission bandwidth of similar to 154 nm and QY similar to 16 % in solid state. Moreover, CD-PDMS phosphor exhibit excellent color rendering index (CRI) similar to 96, the highest reported so far with CIE co-ordinates (0.31, 0.33) that are quite akin to pure white light. Such high performances are achieved due to high quality of CDs and CD-PDMS polymer phosphors by precise control in passivation/functionalization of nanoparticle surface. This work will set platform for the application of CD-phosphor based WLEDs in lighting systems.

Automated summary

In this study, a low-cost, environmentally friendly method of synthesizing single-system white light emitting carbon dots with high quantum yields in both solid and colloidal states was reported. Additionally, a carbon dot polymer phosphor with record emission bandwidth and high color rendering index (CRI) was fabricated, showing potential for high-performance white light emitting diodes in lighting systems.