Self‐Cleaned Photonic‐Enhanced Solar Cells with Nanostructured Parylene‐C

Abstract

Photonic front-coatings with self-cleaning properties are presented as means to enhance the efficiency and outdoor performance of thin-film solar cells, via optical enhancement while simultaneously minimizing soiling-related losses. This was achieved by structuring parylene-C transparent encapsulants using a low-cost and highly-scalable colloidal-lithography methodology. As a result, superhydrophobic surfaces with broadband light-trapping properties were developed. The optimized parylene coatings show remarkably high water contact angles of up to 165.6° and extremely low adhesion, allowing effective surface self-cleaning.The controlled nano/micro-structuring of the surface features also generates strong anti-reflection and light scattering effects, corroborated by numeric electromagnetic modeling, which lead to pronounced photocurrent enhancement along the UV-Visible-Infrared range. The impact of these photonic-structured encapsulants is demonstrated on nanocrystalline silicon solar cells, that show short-circuit current density gains of up to 23.6%, relative to planar reference cells. Furthermore, the improvement of the devices' angular response enables an enhancement of up to 35.2% in the average daily power generation.

Colloidal Lithography for Photovoltaics: An Attractive Route for Light Management

“…Most current solutions to this include the mechanical cleaning of the devices [ 31 ] to expel dust specks via four types of techniques: the robotic method, air-blowing method, water-blowing method, and ultrasonic vibration method. Nevertheless, such type of active mechanical methods requires a power source for enabling the self-cleaning mechanism.…”

“…Concerning passive coating methods, they employ either a superhydrophilic or superhydrophobic film on the outer PV surface. Superhydrophilic coatings reduce the amount of dirt through photocatalytic reactions, while superhydrophobic coatings potentiate the formation of water droplets and their roll-off, carrying away the dirt from the surfaces with minimum water usage [ 31 , 74 ]. To allow water (or other liquids) droplets to effectively roll down a surface, different superhydrophobic-oriented strategies are being investigated mainly via surface micro-structuring, mimicking natural processes such as the skin of certain plant leaves with self-cleaning capability [ 145 ], as further detailed in Section 4.3 .…”

“…To overcome the second drawback, advanced light management techniques must be used to improve the optical response of the devices. From these, light-trapping (LT) schemes that create challenging conditions for light to escape the device have been the topic of many studies [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. The development of photonic structures, implemented via nano-patterning methods [ 32 , 33 ], has been fundamental for PV performance enhancements, for instance by extending the absorption onset to the near-infrared (NIR) region of the solar spectrum [ 34 ].…”

“…It can also produce well-ordered two-dimensional (2D) and three-dimensional (3D) periodic arrays of nanoparticles from various materials on many substrates. Three-dimensional layers are of tremendous interest for photonic crystal-based applications [ 49 ], whereas two-dimensional layers can be used as etching or lithographic masks that can be used for nanofabrication of several structures, specially photonic-enhanced PV devices [ 29 , 31 , 52 ].…”

Evaluation of the cost-effectiveness of grid-connected photovoltaic solar energy in wineries

“…It is important to point out that the current values taken for the costs of the PV corresponded to current data that is always in permanent evolution, and is likely to suffer considerable variations in the coming years. Regarding solar electricity, its cost-per-Watt is expected to keep falling with the development of PV technologies based in higher-efficient solar cells and/or more affordable thin-film PV materials (Enrichi and Righini, 2019;Centeno et al, 2020).…”