Efficient and stable tandem luminescent solar concentrators based on carbon dots and perovskite quantum dots

Zero-Dimensional Perovskite Nanocrystals for Efficient Luminescent Solar Concentrators

Luminescent solar concentrators (LSCs) are large-area sunlight collectors coupled to small area solar cells, for efficient solar-to-electricity conversion. The three key points for the successful market penetration of LSCs are: (i) removal of light losses due to reabsorption during light collection; (ii) high light-to-electrical power conversion efficiency of the final device; (iii) long-term stability of the LSC structure related to the stability of both the matrix and the luminophores. Among various types of fluorophores, carbon quantum dots (C-dots) offer a wide absorption spectrum, high quantum yield, non-toxicity, environmental friendliness, low-cost, and eco-friendly synthetic methods. However, they are characterized by a relatively small Stokes shift, compared to inorganic quantum dots, which limits the highest external optical efficiency that can be obtained for a large-area single-layer LSC (>100 cm2) based on C-dots below 2%. Herein, we report highly efficient large-area LSCs (100–225 cm2) based on colloidal C-dots synthesized via a space-confined vacuum-heating approach. This one batch reaction could produce Gram-scale C-dots with a high quantum yield (QY) (∼65%) using eco-friendly citric acid and urea as precursors. Thanks to their very narrow size distribution, the C-dots produced via the space-confined vacuum-heating approach had a large Stokes shift of 0.53 eV, 50% larger than C-dots synthesized via a standard solvothermal reaction using the same precursors with a similar absorption range. The large-area LSC (15 × 15 × 0.5 cm3) prepared by using polyvinyl pyrrolidone (PVP) polymer as a matrix exhibited an external optical efficiency of 2.2% (under natural sun irradiation, 60 mW cm−2, uncharacterized spectrum). After coupling to silicon solar cells, the LSC exhibited a power conversion efficiency (PCE) of 1.13% under natural sunlight illumination (20 mW cm−2, uncharacterized spectrum). These unprecedented results were obtained by completely suppressing the reabsorption losses during light collection, as proved by optical spectroscopy. These findings demonstrate the possibility of obtaining eco-friendly, high-efficiency, large-area LSCs through scalable production techniques, paving the way to the lab-to-fab transition of this kind of devices.

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Gram-scale synthesis of carbon quantum dots with a large Stokes shift for the fabrication of eco-friendly and high-efficiency luminescent solar concentrators

In recent years, as an energy storage device with a fast charge and discharge speed, long cycle life, and good stability, flexible supercapacitors (SCs) have been extensively used in flexible electronic devices such as smart textiles, flexible display screens, and micro-robots. Combining the advantages of conductive materials and hydrogels, conductive polymer hydrogels have good flexibility, biocompatibility, and adjustable mechanical and electrochemical properties, which enable them to be used as electrolyte or electrode materials for flexible SCs, endowing flexible SCs with various excellent properties and meeting their various working requirements. This paper comprehensively reviews the flexible SCs based on conductive polymer hydrogels, from the design, synthesis and application aspects of conductive polymer hydrogels, the various superior functions (e.g., self-healing, high stretchability and compressibility, high toughness, electrochromic and shape memory) of flexible SCs based on conductive polymer hydrogels to different structures of flexible SCs, including fiber-shaped structures, all-in-one sandwich structures, and in-plane interdigital microstructures. Finally, we summarize the challenges faced by flexible SCs based on conductive polymer hydrogels, which provides new research directions and prospects for future development in this field.

Design and fabrication of conductive polymer hydrogels and their applications in flexible supercapacitors

To date, carbon dots (CDs) or carbon quantum dots (CQDs), considered as alternatives to conventional fluorescent materials such as organic dyes and semiconductor quantum dots (QDs), have drawn significant attention from relevant researchers due to their superior properties, including nontoxicity, biocompatibility, low cost and facile synthesis, and high photoluminescence In particular, doping heteroatoms with CDs can not only dramatically enhance the fluorescence but also greatly improve the electronic structure and doped CDs have been successfully applied in various technological fields Herein, this minireview summarizes recent advances on the synthesis and optical properties of doped CDs and their promising applications for photocatalysis and electrocatalysis Finally, some challenging issues as well as future perspectives of this exciting material are discussed

A minireview on doped carbon dots for photocatalytic and electrocatalytic applications

Luminescent solar concentrators (LSCs) have been widely studied because of their potential importance in industry. A variety of luminescent materials have been developed and used for LSC fabrication such as organic dyes and semiconductor quantum dots. However, fabricating LSCs with a cost-effective method and environmentally friendly materials is a great challenge. Here, N-doped carbon-dots (N-CDs) are for the first time reported to be used as phosphors for LSC fabrication. The properties of N-CDs/PMMA thin film LSCs with various thicknesses are investigated. When the N-CDs/PMMA thin film thickness is 6.67 μm and only one side of LSCs is covered by photovoltaic cells, the performance of the LSCs is optimal, and the values of Voc, Jsc, FF, ηopt and η can reach up to 0.46 V, 13.68 mA cm−2, 62.89%, 4.75% and 3.94%, respectively. Moreover, the photostability of the LSCs is excellent. Results show that N-CDs are able to be effective luminophores for LSC fabrication. Our technique makes the industrial applications of LSCs more feasible since N-CDs have advantages such as high stability, low cost, low toxicity and high photoluminescence quantum yield.

Yunxia Li

Papers

N-doped carbon-dots for luminescent solar concentrators

Fabrication of high-performance luminescent solar concentrators using N-doped carbon dots/PMMA mixed matrix slab

Deep-red emitting zinc and aluminium co-doped copper indium sulfide quantum dots for luminescent solar concentrators.