Back-Junction Solar Cell Structure for Lower Carrier Recombination
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Solution Overview
Problem
Modern solar cells face efficiency degradation due to significant carrier recombination at the p-n junction, limiting the conversion efficiency of Passivated Emitter and Rear Contact (PERC) cells in mass production.
Innovation Solution
A solar cell structure with a p-n junction on the back surface and a first heavily doped layer on the front surface forming a high-low junction, combined with a second heavily doped layer to create a built-in electric field, along with a passivation film structure to reduce recombination and enhance conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single p-n junction structure is used in solar cells, then the device complexity is low, but carrier recombination is significant leading to efficiency degradation
Solution Approach 1:
The solar cell structure is segmented into multiple functional regions: a first heavily doped layer (first conductive type) on the front surface, a second heavily doped layer (second conductive type) on the back surface, and a p-n junction region. This segmentation allows each region to perform specific functions - the first heavily doped layer reduces front surface recombination, the p-n junction enables charge separation, and the second heavily doped layer reduces back surface recombination, collectively improving conversion efficiency while maintaining manageable structural complexity
Solution Approach 2:
Different regions of the solar cell are given different doping concentrations and conductive types to optimize local performance. The first heavily doped layer has high doping concentration of first conductive type to reduce front surface recombination, the p-n junction region has appropriate doping for efficient charge separation, and the second heavily doped layer has high doping concentration of second conductive type to reduce back surface recombination. This local quality differentiation addresses the efficiency-degradation problem without requiring uniform structural changes throughout the device
2Reliability
If additional functional structures are added to improve conversion efficiency, then carrier recombination is reduced, but the device complexity increases
Solution Approach 1:
The patent merges multiple functional structures into a unified solar cell design: the first heavily doped layer is integrated with the front surface, the p-n junction is formed within the substrate, and the second heavily doped layer is integrated with the back surface. This merging approach reduces carrier recombination by providing continuous passivation and optimized charge transport paths, while the integrated design avoids the complexity of separate, discrete components
Solution Approach 2:
The heavily doped layers serve multiple functions simultaneously: they provide surface passivation to reduce recombination, establish electrical contacts for charge collection, and create built-in electric fields to enhance charge separation. This multi-functionality improves conversion efficiency without requiring additional separate structures, thereby limiting the increase in device complexity
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 proposed structure effectively suppresses carrier recombination and enhances electrical conductivity, improving the conversion efficiency of the solar cell.
Implementation Method 1
Solar cells are semiconductor components that utilize the photovoltaic effect to convert light energy into electrical energy
Implementation Method 2
a single p-n junction faces the issue of significant carrier recombination, which leads to efficiency degradation
Implementation Method 3
An electric field that hinders movement of front side carriers is formed between the second heavily doped layer and the semiconductor substrate
Data Source
AI summary
The present disclosure provides a solar cell and a method for preparing the same. The solar cell includes a semiconductor substrate, a first heavily doped layer, a front electrode, an emitter layer, and a back electrode. The first heavily doped layer and the front electrode are disposed on the front surface of the semiconductor substrate. The first heavily doped layer is disposed between the front electrode and the semiconductor substrate. The emitter layer is disposed between the back electrode and the semiconductor substrate.