Carbon-Based Quantum Dots for Photovoltaic Devices: A Review

Abstract

Interest in carbon quantum dots (CQDs) has recently boomed due to their potential to enhance the performance of various solar technologies as nontoxic, naturally abundant, and cleanly produced nanomaterials. CQDs and their other variations, such as nitrogen-doped carbon quantum dots (NCQDs) and graphene quantum dots (GQDs), have improved the performance of luminescent solar concentrators (LSCs) and photovoltaic (PV) cells due to their excellent optical properties. As fluorophores in LSCs, CQDs are mostly transparent to visible light and have absorption/re-emission spectra that can be easily controlled. The outstanding optical properties of CQDs make them promising materials to replace expensive, heavy-metal-based fluorophores. Various CQDs have also been used as or doped into the photoanode, counter electrode, hole transport layer (HTL), and electron transport layer (ETL) of dye-sensitized solar cells (DSSCs), organic solar cells (OSC), perovskite solar cells (PSCs), and other PV cell configurations. The addition of CQDs into the various solar cell components has reduced electron recombination, increased charge density, and boosted electron mobility, improving the performance of the PV cells. Enhancing the power conversion efficiency (PCE) of photovoltaic devices is essential in propagating green energy technology. Thus, CQDs offer an affordable, safe, and environmentally friendly method to advance photovoltaic performance.

Citric Acid-Based Carbon Dots and Their Application in Energy Conversion

“…CA-CDs have been introduced in several types of organic photovoltaics (OPVs), such as dye-sensitized solar cells, perovskite-based solar cells, and bulk heterojunction organic solar cells. 3 In all of these systems, CA-CDs have been applied as photosensitizers, electron acceptors and hole acceptors, UV light downconverters, stabilizers, and more, allowing solar cells with higher power conversion efficiency (PCE) and stability to be achieved (Table 6).…”

“…Low cost and easy to prepare, water-soluble and nontoxic, CDs emerged in the past decade as an excellent alternative to conventional dyes, metal–organic complexes, and semiconductor quantum dots (QDs). Their optical and electronic properties have been exploited for countless analytical, biomedical, and energy conversion applications, such as photocatalysis, light-emitting diodes, and solar cells. − Despite their consistent employment, the chemical nature of CDs and its relationship with their outstanding fluorescence emission are still a topic under debate, with the actual knowledge being incomplete and at times contradictory. A first obstacle to the subject understanding is given by the inconsistent and misused CD terminology, since similar or identical materials have been reported with different names, such as carbon dots, carbon nanodots (CNDs), carbon quantum dots (CQDs), C-dots, and polymer dots (PDs).…”

Development of Doped Carbon Quantum Dot-Based Nanomaterials for Lubricant Additive Applications

“…Moreover, CDs shows uniform size distribution, favorable physicochemical properties, negligible toxicity, and eco-friendliness as well as convenient preparation and functionalization [32]. CDs are also recognized as CQDs (carbon quantum dots) and are very similar to graphene quantum dots (GQDs) [33]. As a zero-dimensional carbon-based nanomaterial, CDs appear to offer a promising solution to a number of challenging scientific and technological problems in the fields of biology, chemistry, and materials [32,[34][35][36].…”

“…Owing to abundance of surface states and quantum effects, CDs possess outstanding physical properties, including tunable photoluminescence. Due to their extraordinary properties, CDs are used for many applications, including bioimaging [39] and biosensing [40], drug delivery [41], solar cells [42], supercapacitors [43], photocatalysis [44], electrocatalysis [45], and photovoltaic devices [33] (Figure 2). To achieve this, CDs are doped with metal and non-metal elements, such as Ga and N, which have been verified as lubricants.…”

Edge-Active Enriched MoS2 Porous Nanosheets as Efficient Pt-Free Catalysts toward the Triiodide Reduction Reaction

“…The triiodide (I 3 – ) reduction reaction (IRR) is an important catalytic reduction process that occurs at the counter electrode (CE) catalyst surface in dye-sensitized solar cells (DSSCs, promising energy conversion devices with eco-friendly nature and high photovoltaic performance that convert clean solar energy directly into usable electricity). − More concretely, proper assembly with the dye-sensitized photoanode, electrolyte containing an iodine-based redox couple (I 3 – /I – ), and CE is essential to achieve satisfactory photoelectric conversion efficiency (PCE). − For a promising DSSC, the level of its PCE, cost, and reliability will directly affect its development space. As we all know, the noble metal platinum (Pt) is still used as the state-of-the-art CE catalyst in the energy conversion field owing to its high catalytic activity and fast electron transfer capability.…”