Microwave irradiation and color converting film application of carbon dots originated from wasted toner powder

Abstract

• First report on the LED application of carbon dots (CDs) derived from wasted toner powder. • The structural and morphological properties of CDs derived from toner powder were investigated by analyzing their transmission electron microscope image, Raman spectra, FT-IR spectra and XPS spectra patterns. • The CDs show the hydrophilic properties, excitation independent emission properties and intense yellow emission (557 nm) under excitation at 300 nm. • The CDs film fabricated by combining CDs solution and polyvinylpyrrolidone emit yellow light under UV LED illuminance, which have potential in LED application. Over the past few decades, sustainable precursor of fluorescent carbon dots (CDs) have been researched due to their environmental benefits, cheap and abundant resource. Among various precursors, waste toner powder is attractive because of its nitrogen-containing organic composition, ever-growing quantity, high toxicity, and low recycling. In this work, we synthesized fluorescent CDs through the microwave irradiation of waste toner powder. The CDs exhibited hydrophilic characteristics and an amorphous structure owing to the microwave irradiation of the waste toner powder in the ethanol solvent. The CDs exhibited dominant yellow emission of 557 nm under 300 nm excitation due to the presence of nitrogen atoms as dopants. To investigate the performance of CDs in LED applications, yellow LEDs were fabricated by combining UV LEDs and CDs. The fabricated LEDs emitted yellow light with (0.411, 0.461) of CIE 1931 coordinates. These results indicate that CDs are favorable luminescent materials for LED applications.