Radiative cooling is a passive cooling strategy with zero consumption of electricity, and it can be used to radiate heat from buildings to reduce air conditioning requirements. Although this technology can work well during optimal atmospheric conditions at nighttime, it is essential to achieve efficient cooling during daytime when peak cooling demand actually occurs. In this article, we report an inexpensive planar polydimethylsiloxane (PDMS)/metal thermal emitter, i.e., a thin film structure, which was fabricated using a fast solution coating process that is scalable for large area manufacturing. By performing tests under different environmental conditions, temperature reductions of 9.5 °C and 11.0 °C were demonstrated in the laboratory and outdoor environment, respectively, with an average cooling power of ~120 W/m 2 for the thin film thermal emitter. In addition, a spectral-selective structure was designed and implemented to suppress the solar input and control the divergence of the thermal emission beam. This enhanced the directionality of the thermal emissions, so the emitter's cooling performance was less dependent on the surrounding environment. Outdoor experiments were performed in Buffalo NY realizing continuous allday cooling of 2~9 °C on a typical clear sunny day at Northern United States latitudes. This practical strategy that cools without electricity input could have a significant impact on global energy consumption.

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Copper­(I) thiocyanate (CuSCN) is a wide bandgap and solution-processable p-type semiconductor with tremendous potential for large-area optoelectronic applications. In this work, chlorine-doped CuSCN (Cl2–CuSCN) was utilized to form a hole transport layer (HTL) for different organic solar cells (OSCs) and inverted perovskite solar cells (PSCs). Chlorine doping into CuSCN thin films is found to improve the device performance of different OSCs, to a level comparable to that of PEDOT:PSS-based OSCs. Notably, the inverted PSCs with Cl2–CuSCN showed a better performance than those with pristine CuSCN or PEDOT:PSS-based inverted PSC devices. Moreover, Cl2–CuSCN-based OSCs and PSCs also reveal significantly better stability than pristine CuSCN and PEDOT:PSS-based devices. Our results show how Cl2–CuSCN thin films act as a universally applicable HTL for emerging solar cell technologies, improving both device performance and stability.

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Copper thiocyanate (CuSCN) is a p-type semiconductor that exhibits hole-transport and wide-band gap (∼3.9 eV) characteristics. However, the conductivity of CuSCN is not sufficiently high, which limits its potential application in optoelectronic devices. Herein, CuSCN thin films were exposed to chlorine using a dry etching system to enhance their electrical properties, yielding a maximum hole concentration of 3 × 10 18 cm –3 . The p-type CuSCN layer was then deposited onto an n-type gallium nitride (GaN) layer to form a prototypical ultraviolet-based photodetector. X-ray photoelectron spectroscopy further demonstrated the interface electronic structures of the heterojunction, confirming a favorable alignment for holes and electrons transport. The ensuing p-CuSCN/n-GaN heterojunction photodetector exhibited a turn-on voltage of 2.3 V, a responsivity of 1.35 A/W at −1 V, and an external quantum efficiency of 5.14 × 10 2 % under illumination with ultraviolet light (peak wavelength of 330 nm). The work opens a new pathway for making a plethora of hybrid optoelectronic devices of inorganic and organic nature by using p-type CuSCN as the hole injection layer.