We introduce and demonstrate the concept of quantumcutting luminescent solar concentrators (QC-LSCs) using Yb 3+ -doped perovskite nanocrystals. These NCs feature a photoluminescence quantum yield approaching 200% and virtually zero self-absorption loss of PL photons, defining a new upper limit of 150% for the internal optical efficiency (η int ) of LSCs that is almost independent of LSC sizes. An unoptimized 25 cm 2 QC-LSC fabricated from Yb 3+ -doped CsPbCl 3 NCs already displayed an η int of 118.1 ± 6.7% that is 2-fold higher than previous records using Mn 2+ -doped quantum dots (QDs). If using CsPbCl x Br 3−x NCs capable of absorbing ∼7.6% of solar photons, the projected external optical efficiency (η ext ) of QC-LSCs can exceed 10% for >100 cm 2 devices, which still remains a challenge in the field. The advantage of QC-LSCs over conventional QD-LSCs becomes especially obvious with increasing LSC sizes, which is predicted to exhibit a more than 4-fold efficiency enhancement in the case of window-size (1 m 2 ) devices.

Epoxy resins with high thermal and mechanical performance as well as good resistance to fire are difficult to synthesize. In this work, a high-performance intrinsically flame-retardant epoxy resin (diglycidyl ether of daidzein (DGED)) was synthesized from renewable daidzein using an efficient one-step process, without the addition of additional flame retardants. The structure of DGED was confirmed by Fourier transform infrared (FTIR), 1 H NMR, and 13 C NMR before it was cured with 4,4′diaminodiphenylmethane (DDM). A commercial diglycidyl ether of bisphenol A (DGEBA) was cured with the same curing agent. Results indicated that the cured DGED/DDM system possessed glass transition temperature (T g ) of up to 205 °C (172 °C for DGEBA/DDM), and tensile strength, tensile modulus, flexural strength, and flexural modulus of 83, 2972, 131, and 2980 MPa, respectively, all much higher than those of cured DGEBA/DDM. The cured DGED/DDM system demonstrated excellent flame-retardant properties, showing a residual char of 42.9% at 800 °C, limiting oxygen index (LOI) of 31.6%, and flammability rating of V-0 in UL94 test. This work provides us an efficient method to prepare high-performance epoxy resin from renewable resource.