Highly Reflective Dielectric Back Reflector for Improved Efficiency of Tandem Thin-Film Solar Cells

Abstract

We report on the prototyping and development of a highly reflective dielectric back reflector for application in thin-film solar cells. The back reflector is fabricated by Snow Globe Coating (SGC), an innovative, simple, and cheap process to deposit a uniform layer of TiO 2 particles which shows remarkably high reflectance over a broad spectrum (average reflectance of 99% from 500 nm to 1100 nm). We apply the highly reflective back reflector to tandem thin-film silicon solar cells and compare its performance with conventional ZnO:Al/Ag reflector. By using SGC back reflector, an enhancement of 0.5 mA/cm 2 in external quantum efficiency of the bottom solar cell and an absolute value of 0.2% enhancement in overall power conversion efficiency are achieved. We also show that the increase in power conversion efficiency is due to the reduction of parasitic absorption at the back contact; that is, the use of the dielectric reflector avoids plasmonic losses at the reference ZnO:Al/Ag back reflector. The Snow Globe Coating process is compatible with other types of solar cells such as crystalline silicon, III-V, and organic photovoltaics. Due to its cost effectiveness, stability, and excellent reflectivity above a wavelength of 400 nm, it has high potential to be applied in industry.

Diffuse reflectors for improving light management in solar cells: a review and outlook

“…SGC is also compared to a textured ZnO:Al/Ag reflector on a-Si:H/μc-Si:H tandem solar cells [30]. The textured ZnO: Al/Ag is considered as the-state-of-the-art reflector for thinfilm photovoltaic devices [66][67][68].…”

“…The benefits of DR, such as low parasitic absorption [29,30], high reflectance [29] and high stability, can also be achieved with wafer based silicon solar cells. This allows us to improve the light trapping at the rear side [31,32].…”

Raytracing Modelling of Infrared Light Management Using Molybdenum Disulfide (MoS2) as a Back-Reflector Layer in a Silicon Heterojunction Solar Cell (SHJ)

“…In general, silicon solar cell back-reflection loss was systematically treated in many pieces of literature with the hopes of addressing back-reflection layer loss as a means for countering the escaped front, escape back and parasitically absorbed light loss using the perfect Lambertian mirror (i.e., BR = 1) [ 8 , 9 , 10 ]. In contrast, throughout the past decades, continuous and sustained development of light trapping technologies has remarkably been improved, reaching today’s hi-tech silicon heterojunction solar cell (SHJ) technology with an efficiency of over 26% in the interdigitated back contacts (IBC) configuration [ 11 , 12 ].…”

Effect of back reflectors on photon absorption in thin-film amorphous silicon solar cells

“…Hydrogenated amorphous silicon (a-Si:H) is a favorite candidate for executing cutting edge thin-film solar cell. In any case, it has a weak absorption of longer wavelength range due to their backhanded material properties, which likewise restrains the general power conversion efficiency (Zeman et al 2000;Muller et al 2001;Green 2006;Hsu et al 2011;Kim et al 2011;Dubey et al 2014;Barugkin et al 2016). In thin-film solar cell utilizing hydrogenated amorphous silicon, the active layer cannot be made thick because of their incited light degradation issue, so it must be thinner (as a rule \320 nm) (Jovanov et al 2013a, b al.…”

“…2013). As an outcome, light trapping or photon management ideas and knowledgeable back contacts are essential for actualizing a useful thin-film amorphous silicon solar cell (Hsu et al 2011;Dubey et al 2014;Barugkin et al 2016). As of late, different light-trapping systems have been severely contemplated where texturing at the surface of the solar cell assumes an explicit part in dispersing and diffracting the incident light through the solar cell structure Ferry et al 2009Ferry et al , 2010Escarre et al 2011;Jovanov et al 2017).…”