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Luminescent solar concentrators (LSCs) are large-area sunlight collectors for efficient solar-to-electricity conversion. The key point for highly efficient LSCs is the choice of fluorophores, which need to have broad absorption, high quantum yield and large Stokes shift. Among various fluorophores, carbon quantum dots (C-dots) hold great promise as eco-friendly alternatives to heavy-metal-containing quantum dots (QDs) due to their adjustable absorption and emission spectra, non-toxicity, low cost and eco-friendly synthetic methods. However, due to the limited absorption band and relatively low quantum yield in the red region, it is a challenge to obtain efficient LSCs based on C-dots. Here, we demonstrated highly efficient LSCs based on red-emissive C-dots. The as-synthesized C-dots have a cubic structure, broad absorption covering 300–600 nm, and red emission (peak located at 595 nm), with a high quantum yield of ∼65% and a large Stokes shift of 0.45 eV. Transient absorption experiments of the C-dots revealed the ultrafast formation of the broad emissive state (1 ps). Based on the excellent optical properties of the C-dots, the as-prepared large-area LSC (10 × 10 × 0.52 cm3) exhibited an optimized external optical efficiency of 4.81% and a power conversion efficiency of 2.41% under natural sun irradiation (70 mW cm−2). Furthermore, a tandem LSC using green-emissive C-dots (top layer) and red-emissive C-dots (bottom layer) as fluorophores exhibited an external optical efficiency as high as 6.78%. These findings demonstrate the possibility of using eco-friendly carbon-based nanomaterials for highly efficient large-area LSCs. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (C-dots) have attracted increasing attention because of their nontoxic composition and excellent optical properties, which have seen them widely used as building blocks for various types of optoelectronic devices. However, the large-scale synthesis of C-dots with a high quantum yield is a big challenge. Herein, C-dots were synthesized via a vacuum heating approach, which could provide over 100 g per batch. The purified C-dots had an ultrahigh quantum yield of ∼79%, absorption peaks at 330 and 405 nm, and a narrow fluorescence spectrum with a main peak centered at 520 nm. As a proof of concept, an as-prepared C-dots/polymer aqueous solution was used as a security ink for textile anti-counterfeiting. After printing the ink into the cotton fabrics, the C-dots still had a quantum yield of 42%. By mixing with other colored C-dots, a multiple colored anti-counterfeiting security code was obtained, which could greatly enhance the anti-counterfeiting level. This study provides a reliable approach to provide high-quality C-dots in a large scale and may open possibilities to use C-dots for potential flexible anti-counterfeiting and optoelectronic applications. [ABSTRACT FROM AUTHOR]

Developing ceramic materials for thermal insulation is vital for various applications. However, ceramics have been considered intrinsically rigid and brittle due to the limited crystallographic slips and structural collapse during service. Their lack of flexibility has hampered many high-end applications of ceramic materials. We developed flexible Al2O3/ZrO2 nanofibrous membranes via sol–gel electrospinning and calcination. Al2O3/ZrO2 nanofibrous membranes had flexibility from −196 °C to 1300 °C and low thermal conductivity (∼0.03166 W m−1 K−1 at room temperature). They also supported 1350-times their weight without suffering structual damage. Hence, Al2O3/ZrO2 nanofibrous membranes could be used for thermal insulation in aerospace and industrial fields, and even in harsh environments. [ABSTRACT FROM AUTHOR]

Luminescent solar concentrators (LSCs) are large-area sunlight collectors, consisting of a waveguide embedded with fluorophores. LSCs could reduce the use of expensive silicon solar cells, thus decreasing the cost of electricity. Although great efforts have been made for fabricating high efficiency large-area LSCs, there is still a lack of knowledge of the temperature effect on the performance of the LSCs based on colloidal quantum dots (QDs) because the LSCs need to be operated in outdoor conditions. In this work, we investigated the thermal effect on the performance of the LSCs based on colloidal QDs upon sunlight irradiation under different temperatures (10–40 °C). The optical properties (e.g. quantum yield and optical efficiency) of the LSCs are strongly dependent on the operating temperature. With increasing operating temperature, the quantum yield and optical efficiency decrease significantly. Among three types of configuration, the LSC based on thin-film QDs coated on glass has the lowest temperature increase under operation, due to the higher thermal conductivity of the glass compared to the polymer matrix. Considering the real operating conditions of the LSCs, the glass-based LSCs have promising potential for future high-efficiency LSC-PV systems. [ABSTRACT FROM AUTHOR]

Correction of 'Solvothermal synthesis of MnFe2O4 colloidal nanocrystal assemblies and their magnetic and electrocatalytic properties' by Zhen Li et al., New J. Chem., 2015, 39, 361–368, https://doi.org/10.1039/C4NJ01466A. [ABSTRACT FROM AUTHOR]

Luminescent solar concentrators (LSCs) are light-weight, semitransparent and large-area sunlight collectors for solar-to-electricity conversion. To date, carbon quantum dots (C-QDs) have attracted a lot of attention due to their size/shape/composition tunable optical properties, high quantum yield, excellent photostability, lower toxicity and simple synthetic methods using earth-abundant and low-cost precursors. However, due to the overlap between their absorption and emission spectra, it is still challenging to fabricate high-efficiency LSCs based on C-dots. In this work, we used C-QDs to fabricate semi-transparent large-area laminated LSCs (10 × 10 cm 2 ). C-QDs have the absorption spectrum ranging from 300 to 550 nm with a Stokes shift of 0.6 eV. By optimizing the concentration of C-QDs, the laminated LSC exhibits a highest η opt of 1.6%, which is 1.6 times higher than that of a single-layer LSC (100 mW cm -2 ). In addition, the laminated LSC exhibits a power conversion efficiency of 0.7% under natural sunlight illumination (62 mW cm -2 ) with excellent photostability. These findings suggest that laminated structured LSCs could be used for efficient solar energy harvesting compared to single layer or tandem structured LSCs based on colloidal C-QDs., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)