Carbon Nanodots as Electron Transport Materials in Organic Light Emitting Diodes and Solar Cells

Abstract

Charge injection and transport interlayers play a crucial role in many classes of optoelectronics, including organic and perovskite ones. Here, we demonstrate the beneficial role of carbon nanodots, both pristine and nitrogen-functionalized, as electron transport materials in organic light emitting diodes (OLEDs) and organic solar cells (OSCs). Pristine (referred to as C-dots) and nitrogen-functionalized (referred to as NC-dots) carbon dots are systematically studied regarding their properties by using cyclic voltammetry, Fourier-transform infrared (FTIR) and UV–Vis absorption spectroscopy in order to reveal their energetic alignment and possible interaction with the organic semiconductor’s emissive layer. Atomic force microscopy unravels the ultra-thin nature of the interlayers. They are next applied as interlayers between an Al metal cathode and a conventional green-yellow copolymer—in particular, (poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(1,4-benzo-{2,1′,3}-thiadiazole)], F8BT)—used as an emissive layer in fluorescent OLEDs. Electrical measurements indicate that both the C-dot- and NC-dot-based OLED devices present significant improvements in their current and luminescent characteristics, mainly due to a decrease in electron injection barrier. Both C-dots and NC-dots are also used as cathode interfacial layers in OSCs with an inverted architecture. An increase of nearly 10% in power conversion efficiency (PCE) for the devices using the C-dots and NC-dots compared to the reference one is achieved. The application of low-cost solution-processed materials in OLEDs and OSCs may contribute to their wide implementation in large-area applications.

Photoluminescent carbon nanodots for artificial photosynthesis

“…Carbon dots (CDs) have captured the scientific community's interest in the relatively new realm of carbon nanostructures [1][2][3][4][5][6]. Their unique attributes, such as photoluminescence, electrochemical potential, compatibility with living organisms, minimal harm, excellent dissolubility in water, chemical endurance, and adaptable surface properties, have sparked great enthusiasm for their potential uses in diverse fields like light-based electronics [7], storing energy [8], stimulating chemical reactions [9], detecting substances [10], and medical applications [11,12].…”