White Light Emitting Diodes with Adjustable Spectral Properties Based on Carbon Quantum Dot-Doped Poly(N-Vinylcarbazole) Composites

A novel class of colloidal carbon materials known as luminescent carbon quantum dots (CQDs) has received a lot of interest lately, particularly in the fields of chemical sensors, bioimaging, nanomedicine, solar cells, light-emitting diode (LED), and electrocatalysis. This work presents an investigation of electroluminescent high performance CQDs with tailored white emission characteristics. The colloidal solvothermal technique and subsequent silica gel column chromatography are used in the current study to create highly luminous CQDs. By employing a host-guest blend as an emissive layer and yellow-emissive CQDs, with 550 nm photoluminescence (PL) peak, as the guest and poly(N-vinylcarbazole) (PVK) as the host, white light electroluminescent CQD-LEDs are fabricated. The configuration used for electroluminescent devices is as follows: ITO/PEDOT:PSS/TFB/CQD:PVK/TPBi/LiF/Al. The carbon dots produce light emission with a full-width-at-half-maximum of 98 nm and high photoluminescence quantum yield of 76%. Optimizing the CQD to PVK ratio systematically shifts the CIE x-y coordinates from 0.23–0.26 to 0.21–0.24, which is located near the cool white region. The structural, morphological, and optical properties of CQD sample and composite films are also investigated. The findings of this study can be regarded as an important effort to reveal the cost effective CQDs for the development of high performance white-LEDs.