Nanomaterials (Dec 2022)

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

  • Zoi Georgiopoulou,
  • Apostolis Verykios,
  • Kalliopi Ladomenou,
  • Katerina Maskanaki,
  • Georgios Chatzigiannakis,
  • Konstantina-Kalliopi Armadorou,
  • Leonidas C. Palilis,
  • Alexander Chroneos,
  • Evangelos K. Evangelou,
  • Spiros Gardelis,
  • Abd. Rashid bin Mohd Yusoff,
  • Athanassios G. Coutsolelos,
  • Konstantinos Aidinis,
  • Maria Vasilopoulou,
  • Anastasia Soultati

DOI
https://doi.org/10.3390/nano13010169
Journal volume & issue
Vol. 13, no. 1
p. 169

Abstract

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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.

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