Light Management in Crystalline Silicon Solar Cells with Photonic Nanocoatings

• Autor(a) principal: Santos, Ivan Miranda
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/155362
• topic: Photovoltaics; Light Management; Colloidal Lithography; Crystalline Silicon; Solar Cells; Photonic Nanostructured Coatings; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia dos Materiais

Light management via photonic nanostructured coatings sustains a broad set of possible solar energy conversion enhancements, alternatively to conventional texturing processes that deteriorate solar cells (SCs) electrical transport through charge carrier recombination losses. These coatings, composed of high-refractive index materials structured at the sunlight wavelengths scale, can improve SCs efficiency, avoiding surface texturing processes while still allowing high-performance light trapping (LT). Here, through a highly scalable colloidal lithography methodology, proposed titanium dioxide (TiO2) nanovoid coatings were patterned on conventional (250 μm) and thin (90 μm) flat crystalline silicon (c-Si) wafers. These nanostructured coatings were also applied on textured (130 μm c-Si absorber), etched (140 μm) and flat (740 μm) c-Si interdigitated back contact solar cells (IBCSCs). The subsequent broadband absorption amplification was owing to the combined effects of (1) light scattering in near-infrared (NIR) wavelengths and (2) broad anti-reflection. With coated 250 μm c-Si wafers, a photocurrent density (ℎ) of 36.6 mA/cm2 was determined by absorption spectrum integration between 350 and 1200 nm. Approximately 84 % of the maximum theoretical ℎ Lambertian LT limit is here attained with 669 and 693 nm of TiO2 thin photonic nanostructured coatings, respectively with the considered conventional and thin c-Si wafers. When integrated into test devices, outstanding optical improvements are attained without diminishing the original electrical performance by applying coatings with TiO2 thicknesses ≥ 545 nm. Unprecedent ~30 % of efficiency enhancement and 31.9 mA/cm2 of short-circuit current density () are demonstrated with etched IBCSCs coated with 885 nm of TiO2 nanostructured coating. Additionally, unmatched optical angular acceptance is shown: 63 % of efficiency and 68 % of enhancements are respectively exhibited with 545 and 885 nm of TiO2 coatings for 80° of light incidence angle. Hence, with straightforward near-future integration in the established industry, a highly promising path for c-Si photovoltaic improvement is entailed.