Preparation of dual-emission peak lignin-derived carbon dots and their application in WLEDs

White light-emitting diodes (WLEDs), as strong contenders for future solid-state light sources, hold significant promise in solid-state lighting due to their high efficiency, low power consumption, self-emission, and versatility. Carbon dots (CDs), a novel type of carbon nanomaterials, exhibit excellent luminescence properties. However, their intricate structure and unclear fluorescence mechanism hinder long-wavelength modulation, and solid-state aggregation leads to luminescence quenching, limiting their application in optoelectronic devices. This study focuses on the preparation of CDs with dual yellow–green emission peaks via a hydrothermal method using sodium lignosulfonate as a carbon source. The mechanism behind the dual emission is elucidated by analyzing the morphology and chemical composition of the CDs. Specifically, the green light originates from surface-related states due to N doping, while the yellow light results from the carbon-core state at higher hydrothermal temperatures. By incorporating these CDs into transparent wood, a material capable of emitting white light under blue light excitation is achieved. This transparent wood was successfully applied in the fabrication of WLEDs, providing valuable insights into CDs modulation and their utilization for white light solid-state lighting applications.