Surface modification of color-clarifying layer in transparent conductive oxide based distributed Bragg reflector-diffuser electrode for building-integrated photovoltaics

We fabricated a colored transparent thin-film silicon solar cell (TSC) using a transparent distributed Bragg reflector (DBR) electrode for building-integrated photovoltaics (BIPVs). To construct a transparent DBR electrode, indium tin oxide (ITO) and aluminum-doped zinc oxide (AZO) were optimized with the variation of oxygen incorporation considering optical and electrical properties in reactive sputtering deposition, and their refractive index difference was about 0.12 at a wavelength of 480 nm, which generate low reflection loss for TSCs. To improve color clarity and PV performance, the surface morphology of the AZO diffuser layer was modified by varying chemical etching times. Their optical and electrical properties and the applied PV characteristics were investigated, and the figure of merit (FOM) was introduced for evaluation considering PV performance, transmittance, and blue color coordinate, which is the highest at an etching time of 40 s. The surface modification of the DBR electrode and the evaluation using FOM is expected to aid in developing BIPVs, considering their utility and aesthetics. It is expected to apply to TSC using various absorber materials for color realization.