Thin Film Solar Cells With Textured Microlens Arrays
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Solution Overview
Problem
Thin-film solar cells face challenges in enhancing light trapping and reducing reflection losses, which limits their efficiency due to their thin thickness and higher surface recombination losses, especially when compared to traditional solar cells.
Innovation Solution
A transparent microlens array (MLA) is applied to the surface of thin-film solar cells, comprising an array of lenses that refract and redirect light to increase the light path length within the active layer, thereby enhancing light absorption and reducing reflection losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the solar cell thickness is reduced to minimize material usage, then manufacturing cost is reduced, but light absorption efficiency decreases
Solution Approach 1:
The invention enhances light absorption in the thin active layer by introducing a textured surface structure that extends the light path through scattering effects. The textured layer creates multiple internal reflections and extends the effective optical path length, allowing thin-film cells to absorb light more efficiently without increasing material thickness.
2Loss of energy
If anti-reflection coatings are applied to reduce reflection loss, then light absorption is improved, but the solution becomes more complex with multiple layers
Solution Approach 1:
The transparent resin layer serves multiple functions simultaneously: it acts as an anti-reflection coating to reduce surface reflection, fills the voids between textured features to reduce surface recombination, and provides mechanical support. This multi-functionality reduces the need for separate anti-reflection layers, simplifying the overall device structure.
3Loss of energy
If surface texturing is applied to increase light trapping, then light path length is increased, but manufacturing precision requirements increase
Solution Approach 1:
The invention employs a porous or textured surface structure that can be fabricated using relatively simple processes. The textured layer provides effective light trapping through scattering, while the transparent resin fills the resulting voids to create a smooth outer surface, reducing the precision requirements for the texturing process itself.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The MLA increases the short-circuit current and power conversion efficiency by 20-30% or more by altering the light path and reducing surface reflectance, making it suitable for large-area thin-film solar cells with minimal modification to existing processing steps.
Implementation Method 1
the light over a given area is focused and directed to a smaller area cell such that more energy than that possible without the focusing can be absorbed by the cell
Implementation Method 2
Solar concentrators are one way by which performance of a photovoltaic device can be enhanced. In this manner, the light over a given area is focused and directed to a smaller area cell
Implementation Method 3
The anti-reflection coating minimizes reflection when its refractive index is the geometric mean of the materials on either side of the coating
Implementation Method 4
Any roughening of the exposed surface reduces reflection by increasing the probability that reflected light is also projected onto a portion of the surface
Data Source
AI summary
Textured transparent layers are formed on the incident light receiving surface of thin film solar cells to increase their efficiency by altering the incident light path and capturing a portion of the light reflected at the MLA. The textured transparent layer is an array of lenses of micrometer proportions such as hemispheres, hemi-ellipsoids, partial-spheres, partial-ellipsoids, cones, pyramids, prisms, half cylinders, or combinations thereof. A method of forming the textured transparent layer to the light incident surface of the solar cell is by forming an array of lenses from a photocurable resin and its subsequent curing. The photocurable resin can be applied by inkjet printing or can be applied by roll to roll imprinting or stamping with a mold.