Abstract
To promote the efficiency of thermophotovoltaic (TPV) devices, the spectral management based on micro/nanoscale structure plays a significant role. In this paper, we design a four-layer filter that consists of Ag, ZnS and MgF2 nanoscale-thickness layers for a GaSb TPV cell. By realizing a transmission spectrum with a sharp cut-off, an appropriate bandwidth and a near-perfect reflectance in the cell’s out-of-band (OOB) wavelength range, we demonstrate based on an experimentally validated model that an efficiency of 24.8% and an electrical output power density of 0.86 W/cm2 are achieved when the filter is incorporated with a GaSb cell and an 1500°C-blackbody emitter. Besides, the filter ensures the decrease in efficiency accompanied by the increase of illumination intensity of the cell is less than 5% within the temperature range of 987°C. As a front-surface spectral management, the filter imposes minimal demands on the low OOB absorption characteristics of cell materials, which consequently provides an expanded design latitude for cell engineering. It is believed that our filter will shed light on the spectral management route that is different from the method based on back side reflector to realize efficient TPV systems.
