Tandem Solar Cell Recombination Layer for Lower Optical Loss
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Solution Overview
Problem
Current tandem solar cells have a significant gap between actual and theoretical photoelectric conversion efficiency, and their structure needs optimization to improve efficiency.
Innovation Solution
A solar cell structure is proposed, comprising a bottom cell, a recombination layer with alternating transparent conductive layers and metal layers, and a top cell. The recombination layer enhances conductivity while reducing thickness and parasitic light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a tandem solar cell structure is used to improve photoelectric conversion efficiency, then the energy utilization rate of sunlight increases, but the actual efficiency falls short of theoretical efficiency due to structural limitations
Solution Approach 1:
The tandem solar cell is divided into two separate cells (top cell and bottom cell) with different bandgaps, each optimized for specific wavelength ranges. The recombination layer is segmented into multiple sub-layers (intrinsic layer and doped layers) to handle different functions of carrier recombination and transport independently, resolving the structural complexity while maintaining high efficiency
Solution Approach 2:
An intrinsic semiconductor layer is introduced as an intermediary between the top and bottom cells to facilitate carrier recombination. This intermediate layer acts as a mediator that enables efficient charge transfer while maintaining optical transparency, bridging the gap between the two cells with different bandgaps
2Reliability
If the recombination layer thickness is increased to improve carrier recombination efficiency, then carrier loss decreases, but parasitic light absorption increases
Solution Approach 1:
The recombination layer is designed with spatially varying doping concentrations, creating regions with different electrical properties at different locations. The intrinsic layer provides high optical quality for light transmission, while doped regions provide electrical functionality for carrier recombination, allowing the layer to be thin without sacrificing recombination efficiency
Solution Approach 2:
The recombination layer uses a composite structure combining intrinsic semiconductor material with doped semiconductor materials. This composite approach allows the layer to simultaneously achieve high optical transparency (from the intrinsic material) and high electrical conductivity (from the doped material), reducing both thickness requirements and parasitic absorption
3Illumination intensity
If transparent conductive layers are used in the recombination layer to maintain light transmission, then optical quality is preserved, but electrical conductivity is insufficient
Solution Approach 1:
The patent merges the functions of optical transparency and electrical conductivity into a single recombination layer by combining intrinsic semiconductor material (for optical quality) with doped semiconductor material (for electrical conductivity). This unified structure eliminates the need for separate transparent conductive oxide layers while achieving both requirements simultaneously
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 improves carrier recombination efficiency, reduces carrier loss, and enhances the filling factor and photoelectric conversion efficiency of the solar cell.
Implementation Method 1
The recombination layer is disposed between the second semiconductor conductive layer and the top cell and includes at least two transparent conductive layers and at least one metal layer that are alternatingly stacked in the first direction
Implementation Method 2
Because of its good photoelectric conversion efficiency, solar cells have become the development focus of clean energy utilization
Data Source
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AI summary
Embodiments of the disclosure relate to a solar cell and a photovoltaic module, where the solar cell includes a bottom cell, a recombination layer, and a top cell which are stacked in sequence in a first direction. The bottom cell includes a first semiconductor conductive layer, a substrate, and a second semiconductor conductive layer that are stacked in sequence in the first direction, and the second semiconductor conductive layer is disposed between the substrate and the top cell. The recombination layer is disposed between the second semiconductor conductive layer and the top cell and includes transparent conductive layers and at least one metal layer that are alternatingly stacked in the first direction, a top layer and a bottom layer of the recombination layer are both transparent conductive layers.