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.

中文翻译：

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具有大斯托克斯位移的克级合成碳量子点，用于制造环保和高效的发光太阳能聚光器

发光太阳能集中器（LSC）是与小面积太阳能电池耦合的大面积阳光收集器，用于高效的太阳能发电。LSC成功进入市场的三个关键点是：（i）消除了由于光收集过程中的重吸收而造成的光损失；（ii）最终设备的光电转换效率高；（iii）LSC结构的长期稳定性与基质和发光体的稳定性有关。在各种类型的荧光团中，碳量子点（C-dots）提供了宽吸收光谱，高量子产率，无毒，环保，低成本和环保的合成方法。但是，与无机量子点相比，它们的斯托克斯位移相对较小，²）基于低于2％的C点。在此，我们报告了一种高效的大面积LSC（100-225 cm ²），它是基于通过空间受限的真空加热方法合成的胶体C点而得到的。使用生态友好型柠檬酸和尿素作为前体，这一批反应可以产生具有高量子产率（QY）（〜65％）的革兰氏级C点。由于其非常窄的尺寸分布，通过空间受限的真空加热方法生产的C点的斯托克斯位移为0.53 eV，比通过使用相同前驱体和相同溶剂的标准溶剂热反应合成的C点大50％。吸收范围相似。大面积LSC（15×15×0.5 cm ³通过使用聚乙烯吡咯烷酮（PVP）聚合物作为基质制备的）显示出2.2％的外部光学效率（在自然阳光照射下，60 mW cm ^-2，未表征的光谱）。在耦合到硅太阳能电池之后，LSC在自然阳光照射（20 mW cm ^-2，未表征的光谱）下表现出1.13％的功率转换效率（PCE ）。如光谱学所证明的，通过完全抑制集光期间的重吸收损失，获得了这些空前的结果。这些发现表明，通过可扩展的生产技术可以获得环保，高效，大面积LSC的可能性，为这种设备从实验室到工厂的过渡铺平了道路。