Jieyan Zhao,Yingnan Song,Zengchao Yang,Yong Li,Jiangtao Li
Daytime radiative cooling enables passive cooling of objects without consuming energy. However, it is a challenge for most radiative cooling films to achieve exceptional solar reflectivity , infrared emissivity and thermal conductivity simultaneously, which limits their applications in above-ambient conditions such as electrical equipment . Herein, we prepare highly solar-reflective β -Si 3 N 4 dielectric particles with solar reflectivity exceeding 0.91 and atmospheric window emissivity of 0.93 by one-step combustion synthesis . The radiative cooling film consisted of β -Si 3 N 4 particles and PVDF matrix achieves a subambient cooling performance of 11.63 °C and theoretically yields a radiative cooling power of 45.41 W m −2 in the daytime. Futhermore, the film exhibits high thermal conductivity of 3.19 W m −1 K −1 due to the heat conducting pathways constructed by elongated rod-like β -Si 3 N 4 particles, which leads to a remarkable temperature drop of 5.00 °C when be applied on the surface of 5 W LED. The film reported here provides a practical option for the efficient radiative cooling and heat dissipation of electrical equipment.
Yongrun Dong,Wen Li,Tao Huang,Shuaigang Ge,Linghang Kong,Chuang Ning,Zequan Li,Wei Gao,Bingsuo Zou
Recently, lead-free double perovskites have been regarded as a promising alternative to lead halide perovskites due to their wide emission band, and environmental protection and stability properties, and are expected to become a series of rising star materials in the lighting field. However, currently, the growth of most lead-free double perovskites occurs in the strong acid environment, which not only brings high cost and environment risk, but also makes it hard to realize large-scale applications with powder products. Herein, we apply a strategy of in situ synthesis of lead-free double perovskites in a polymer matrix by using a small amount of precursors and relatively friendly DMSO solvent to obtain efficiently luminescent Sb3+/Mn2+ co-doped Cs2KInCl6/PVDF composite films in a large-area. The co-doping of Mn2+/Sb3+ into this inorganic double perovskite matrix makes microcrystals with good crystallinity and size distribution in this polymer. The as prepared co-doping composite film with Mn/Sb feeding ratio 16 : 1 shows the brightest white light emission under 320 nm excitation, with a photoluminescence quantum yield (PLQY) as high as 86.98%. The energy transfer (E-T) from the charge-transfer band to the triplet self-trapped exciton (STE) around Sb3+ and then to the ferromagnetic (FM) coupled Mn2+ pair 3d state was confirmed by the temperature-dependent PL spectra and density functional theory calculations. Finally, a single-compound white light emitting diode with chromatic coordinates of (0.31, 0.33) and fluorescent anti-counterfeiting labels could be fabricated based on this composite film with the best white emission. This work provides a new strategy for the application of lead-free double perovskites in the fields of lighting and anti-counterfeiting.
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