MONOLITHIC, SELF-POWERED PHOTOVOLTAIC-ELECTROCHROMIC COATING FOR WINDOWS

We report progress in the development of a monolithic, self-powered ph otovoltaic-electrochromic coating for energy-conserving windows. The c oating employs an all solid-state electrochromic device based on Li-do ped WO, as an optical transmittance modulator and a wide-bandgap amorp hous SiC alloy (a-SiC:H) photovoltaic (PV) cell as an integral power s ource. The electrochromic device is deposited together with the PV dev ice as a monolithic coating on a glass substrate. The active Li-ion co ncentration in the electrochromic device was optimized based on the th ermodynamics and optical properties of the electrochromic and ion-stor age layers. Electrical and electro-optic characteristics of the multil ayer coatings are reported. The monolithic tandem PV-electrochromic co ating shows a transmittance variation of more than 60% under 1 sun ill umination.