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This study proposes an image colour analysis tool that could help graphic/product designers to understand colour distribution and colour appearance of a series product. The analysis method is in accordance with the CIELab uniform colour space created by the International Commission on Illumination (CIE) in 1976. Based on the analysis method used in a previous study of the oil paintings, 370 oil paintings were analysed. The results demonstrated that using simple colour difference formula could reveal the images’ numerical colour distribution (Tsai, 2019). The focus of this study is twofold: to understand the colour appearance of product design and to check the rationality and reliability of the analysis tool. The analysis tool this study proposes could also be useful in providing the product designers with easy analysis and understanding of the colour distribution of images.

Abstract: A graphene oxide (GO) film is functionalized with metal (Au) and metal‐oxide (MoOx) nanoparticles (NPs) as a hole‐extraction layer for high‐performance inverted planar‐heterojunction perovskite solar cells (PSCs). These NPs can increase the work function of GO, which is confirmed with X‐ray photoelectron spectra, Kelvin probe force microscopy, and ultraviolet photoelectron spectra measurements. The down‐shifts of work functions lead to a decreased level of potential energy and hence increased Voc of the PSC devices. Although the GO‐AuNP film shows rapid hole extraction and increased Voc, a Jsc improvement is not observed because of localization of the extracted holes inside the AuNP that leads to rapid charge recombination, which is confirmed with transient photoelectric measurements. The power conversion efficiency (PCE) of the GO‐AuNP device attains 14.6%, which is comparable with that of the GO‐based device (14.4%). In contrast, the rapid hole extraction from perovskite to the GO‐MoOx layer does not cause trapping of holes and delocalization of holes in the GO film accelerates rapid charge transfer to the indium tin oxide substrate; charge recombination in the perovskite/GO‐MoOx interface is hence significantly retarded. The GO‐MoOx device consequently shows significantly enhanced Voc and Jsc, for which its device performance attains PCE of 16.7% with great reproducibility and enduring stability. [ABSTRACT FROM AUTHOR]

Solar cells with high efficiency, low cost, and high stability are the target for the new generation of solar cells. A fully printable perovskite (CH 3 NH 3 PbI 3 ) solar cell (PSC) with device architecture FTO/TiO 2 /Al 2 O 3 /NiO x /C is fabricated in the current research as a low-cost and relatively stable structure and is investigated to determine how different fabrication factors such as the thickness of the insulating spacer layer (Al 2 O 3 ) or treatments such as heat and UV-O 3 treatments can affect the interfacial properties of this multilayer mesoporous structure. X-ray photoelectron spectra (XPS) show that UV-O 3 treatment increases the Ni 3+ (Ni 2 O 3 ) phase on the surface of the black nickel oxide layer leading to better charge extraction and increasing open-circuit voltage (V OC ) up to 0.945 V. We observe improved CH 3 NH 3 PbI 3 formation inside the mesoporous layers by the PbI 2 penetration at a higher temperature. Impedance spectral together with current-voltage measurements show the effect of thickness for the insulator layer in the internal and interfacial resistances and photovoltaic characteristics of the cell. The best performance of the carbon-based PSC attains power conversion efficiency of 12.1% with the thickness of the Al 2 O 3 layer at 450 nm.