Perovskite-on-Silicon Multi-Junction PV Efficiency Gain
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Solution Overview
Problem
Current monolithically integrated perovskite-on-silicon multi-junction photovoltaic devices experience a net loss in power conversion efficiency compared to single junction silicon cells, limiting their effectiveness.
Innovation Solution
A monolithically integrated perovskite-on-silicon multi-junction photovoltaic device is developed, featuring a perovskite sub-cell with a planar heterojunction structure and a silicon heterojunction sub-cell, where the perovskite material is of the formula AxA′1-xB(XyX′3, with A being formamidinium and A′ as caesium, B as lead, and X and X′ as iodide and bromide, and the surface of the silicon sub-cell is textured with a roughness average of 50-450 nm to facilitate conformal deposition of the perovskite layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a monolithically integrated perovskite-on-silicon multi-junction photovoltaic device is constructed, then the power conversion efficiency should be improved over single junction silicon cells, but previous devices experienced a net loss in efficiency
Solution Approach 1:
The device is divided into two distinct sub-cells: a top perovskite sub-cell and a bottom silicon sub-cell. Each sub-cell is optimized independently for its specific function, with the perovskite sub-cell capturing high-energy photons and the silicon sub-cell capturing lower-energy photons, thereby resolving the efficiency loss through functional segmentation
Solution Approach 2:
The perovskite sub-cell is nested on top of the silicon sub-cell in a vertically stacked configuration. The textured rear surface of the perovskite sub-cell serves as both the optical interface and the mechanical support for the silicon sub-cell, creating a nested structure where one cell is integrated upon the other to achieve space-efficient multi-junction functionality
2Use of energy by moving object
If the silicon sub-cell surface is textured to enhance light trapping, then light absorption is improved, but conformal deposition of the perovskite layer becomes difficult
Solution Approach 1:
The rear surface of the perovskite sub-cell is textured with a controlled roughness profile featuring curved features with radii of curvature between 1-10 micrometers. This curvature enables conformal deposition of the perovskite layer by allowing the material to follow the surface contours, while simultaneously enhancing light trapping through multiple internal reflections within the curved structures
Solution Approach 2:
The surface texture is engineered with specific local characteristics: roughness values of 50-450 nm and controlled curvature radii of 1-10 micrometers. These localized geometric features are optimized to provide different functions at different scales - the fine roughness enables conformal deposition while the larger curvature features enhance light trapping, resolving the contradiction between deposition quality and light absorption
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
This configuration achieves a net gain in power conversion efficiency over the single junction silicon sub-cell, enhancing the overall efficiency of the multi-junction device while maintaining the benefits of textured silicon surfaces.
Implementation Method 1
a photoactive region comprising a layer of perovskite material... Electrons are able to transition from one energy band to another, but each transition requires a specific minimum energy and the amount of energy required will be different for different materials. The electrons acquire the energy needed for the transition by absorbing either a phonon (heat) or a photon (light).
Implementation Method 2
a surface of the silicon sub-cell is textured with a roughness average of 50-450 nm to facilitate conformal deposition of the perovskite layer
Data Source
AI summary
There is provided a multi-junction photovoltaic device comprising a first sub-cell disposed over a second sub-cell, the first sub-cell comprising a photoactive region comprising a layer of perovskite material and the second sub-cell comprising a silicon heterojunction (SHJ).