Transparent electrode of ITO/AZO DBR-diffuser structure to implement various and vivid colors for BIPV windows

For building-integrated photovoltaic windows, colored transparent hydrogenated amorphous silicon solar cells and modules were fabricated using a transparent electrode structure of a distributed Bragg reflector (DBR) and diffuser. The transparent DBR-diffuser electrode consists of multiple layers of indium tin oxide and Al-doped zinc oxide. This optically functional electrode not only implements various colors but also enhances color clarity. The transparent DBR-diffuser electrodes were designed using optical simulation and exhibited a wide color range of blue, green, and red by simply changing the thicknesses of the indium tin oxide and Al-doped zinc oxide layers. Using only eight pairs of DBRs, the electrode showed vivid colors and suppressed color noise by 23% with the diffuser structure. Because the color can be realized with a small amount of reflected light, the efficiency of transparent solar cells does not differ substantially in color. The developed transparent DBR-diffuser electrode can be widely applied to improve the color quality of both opaque and transparent solar cells and modules composed of various materials. • Colored solar cell and module for BIPV were fabricated. • ITO and AZO were deposited alternatively to utilize DBR scheme. • AZO diffuser is competitive condition for higher color quality. • Color qualities of solar cells were investigated on the CIE 1931 chromaticity. • Characteristics of transparent a-Si:H solar cells with various colors were examined.