Colloidal Lithography for Light Trapping in Flexible Thin Film Solar Cells

• Autor(a) principal: Boane, Jenny Luis Nhaliguangue
• Data de Publicação: 2024
• Idioma: eng
• Título da fonte: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Texto Completo: http://hdl.handle.net/10362/178518
• topic: Photovoltaics; Photonics; Colloidal Lithography; Transparent Microstructured electrodes UV Sensors; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia dos Materiais

The demand for more efficient, reliable, and economical optoelectronic and photovoltaic (PV) devices has led researchers to explore nano/microtechnological solutions. These solu- tions aim to enhance PV performance without significantly increasing production costs. Among these, photonic structures based on wavelength-sized transparent conductive oxides (TCOs) are particularly promising. They improve efficiency by reducing reflection and opti- mizing light absorption inside the solar cells, as well as in other photodetector devices like UV sensors. In this work, we developed a simple, low-cost, versatile, and highly scalable colloidal lithography process to fabricate and optimize three different microstructures: indium zinc ox- ide (IZO), indium tin oxide (ITO), and titanium dioxide (TiO2). These microstructures, with wavelength-sized features, were smoothly modelled on flexible ITO substrates coated with polyethylene terephthalate (PET), parylene C membranes, and rigid substrates (glass) coated with ITO. The ITO micro-mesh demonstrated enhanced transparent electrode properties, showing significant light interaction with a pronounced light scattering performance (diffuse transmission up to ~50%). Additionally, the microstructured photonic mesh of TCOs allowed for a greater volume of material in the electrode while maintaining desired transparency, lead- ing to a reduction in sheet resistance (~14%) and improved electrical benefits due to enhanced contact conductance. When integrated into perovskite solar cell test devices, these microstruc- tured photonic meshes provided excellent optical improvements, yielding short-circuit pho- tocurrent gains of up to ~20% and efficiency gains of up to ~17%, closely matching the values predicted by modelling optimizations. In view of exploring other promising applications, the microstructuring of test parylene- C membranes was investigated in UV sensors. This resulted in a pronouncedly enhanced pho- tocurrent response when compared with non-structured devices. These findings pave the way for a new class of transparent photonic electrodes with mechanical flexibility. They hold strong potential not only as advanced front contacts for thin- film foldable solar cells but also for a wide range of optoelectronic applications.