The Role of Carbon Quantum Dots in Organic Photovoltaics: A Short Overview

Abstract

Carbon quantum dots (CDs) are a new class of fluorescent carbonaceous nanomaterials that were casually discovered in 2004. Since then, they have become object of great interest in the scientific community because of their peculiar optical properties (e.g., size-dependent and excitation wavelength-dependent fluorescence), which make them very similar to the well-known semiconductor quantum dots and suitable for application in photovoltaic devices (PVs). In fact, with appropriate structural engineering, it is possible to modulate CDs photoluminescence properties, band gap, and energy levels in order to realize the band matching suitable to enable the desired directional flow of charge carriers within the PV device architecture in which they are implanted. Considering the latest developments, in the present short review, the employment of CDs in organic photovoltaic devices (OPVs) will be summarized, in order to study the role played by these nanomaterials in the improvement of the performances of the devices. After a first brief summary of the strategies of structural engineering of CDs and the effects on their optical properties, the attention will be devoted to the recent highlights of CDs application in organic solar cells (OSCs) and in dye sensitized solar cells (DSSCs), in order to guide the users towards the full exploitation of the use of these nanomaterials in such OPV devices.

A review on advancements in carbon quantum dots and their application in photovoltaics

“…128 As a result, CQDs-based solar cells are expected to display superior performance. This article reports two recent reviews 119,128 that deal with the role of CQDs in specic types of solar cells. However, the present section is not restricted to any specic type but rather discusses the various possible roles of CQDs in different types of solar cells exploited by the researchers.…”

“…Therefore, CQDs are the best alternatives that offer a win-win situation over the said materials. 119,147 In 2016, Soa Paulo et al synthesized CQDs from citric acid and p-phenylenediamine using a hydrothermal approach. The cyclic voltammetry measurements conrmed that the HOMO and LUMO energy levels of CQDs are suitable for hole transfer and electron blocking from the perovskite to CQDs.…”

“…Solar energy is a green and inexhaustible energy resource that, if exploited fully, can bring a paradigm shift and make the planet earth completely free from fossil fuel-based electricity generation. 119 Solar cells are electronic devices (consisting of p–n junctions) that convert light into electricity through the photovoltaic (PV) effect. Research efforts have led to the development of different categories of solar cells like single or multi-junction semiconductor solar cells (Si or GaAs based), thin-film solar cells, quantum dot solar cells, organic/polymer solar cells, perovskite solar cells, dye-sensitized solar cells, etc.…”

“…Therefore, CQDs are the best alternatives that offer a win–win situation over the said materials. 119,147 …”

Recent Applications of Carbon Nanotubes in Organic Solar Cells

“…In this respect, carbon-based materials, such as graphitic carbon nitride, carbon quantum dots, carbon nanotubes (CNTs) and graphene ( Jeon et al, 2018b ; Nguyen et al, 2019 ; Ouyang, 2019 ; Hu et al, 2020 ; Pan et al, 2020 ; Qin et al, 2020 ; Subramanyam et al, 2020 ; Shin et al, 2021 ; Vercelli, 2021 ), have attracted considerable research attention due to their unique physicochemical properties, low-cost, natural abundance of carbon, non-toxicity and compatibility with large-scale solution synthesis ( Delacou et al, 2017 ). Among these, CNTs are more appealing owing to their large specific surface area, tunable band gap, high optical transmittance in the visible region, competitive electrical conductivity, high charge carrier mobility, excellent flexibility and superior mechanical, thermal and chemical stability ( Khan et al, 2018 ; Oseni et al, 2018 ).…”