ALD-deposited thin films as functional layers in coloured silicon solar cells

Abstract

This work explores the use of atomic layer deposited (ALD) ZnO thin films as functional and aesthetic layers in monocrystalline silicon solar cells. ZnO films of varying thickness were deposited on polished silicon wafers and finished solar cells producing distinct interference colours – gold, violet, and green – while enabling precise control over optical properties. Colorimetric analyses in RGB and CIE Lab colour spaces confirmed the tunability of the perceived colour with increasing ZnO thickness. Raman spectroscopy and X-ray fluorescence verified crystalline quality and composition of the ZnO films, while spectroscopic reflectometry demonstrated thickness uniformity and growth rates consistent with ALD characteristics. The deposition of ZnO layers reduced the power conversion efficiency of the solar cells from ~ 15.2% to ~ 13.5%, highlighting a trade-off between aesthetics and photovoltaic performance. Nevertheless, the coloured ZnO coatings exhibited potential for integrating photovoltaic modules into architecturally sensitive environments where visual harmony is desired. The results underline the versatility of ALD technology in engineering both the optical and functional properties of solar cells through a controlled thin-film deposition.