Design of nano/micro–structured surfaces for efficiently harvesting and managing full–spectrum solar energy

Abstract

The proposed photovoltaic (PV)–Thermoelectric (TE) hybrid system is an advanced approach to utilize full–spectrum (300–2500 nm) solar energy. In this system, incident photons in different wavelengths must be transferred to different devices via efficient allocation, which is called photon management, to enhance the performance of the hybrid systems. The photon–management property can be realized through subwavelength structures in solar cells. In this work, based on silicon solar cells, composite subwavelength structures are fabricated in crystalline silicon through ICP etching and magnetron sputtering process with the required spectral characteristics. Integrated ordered, and disordered nanopillar/nanohole arrays enable broadband absorption in the wavelength range (300–1100 nm) above the bandgap with an average absorptance of about 97%. About 60% solar energy from 1200 nm to 2500 nm can transmit to the TE devices with the assistance of the deposited TiO2/SiO2 bilayer films on the bottom side. The good photon–management performance is independent of the incident angles and insensitive to the polarization states. The method can also be applied to other kinds of solar cells for the application in the PV–TE hybrid systems. This paper opens new routes to smart photon management, which is expected to have promising applications in efficient full–spectrum solar energy conversion.