Solar Cell Fabrication with Selective Emitter and Back Surface Field
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Solution Overview
Problem
The challenge lies in achieving high-efficiency, cost-effective mass production of slim-type silicon solar cells with improved photovoltaic performance, particularly in forming an emitter layer on ultra-thin silicon substrates while maintaining reliability and quality, and reducing production costs and time.
Innovation Solution
A fabrication method involving doping a silicon substrate with a first conductive type impurity and a second conductive type impurity to form an emitter layer, followed by forming an antireflection film, front and rear electrodes, and a back surface field layer with different impurity concentrations, allowing for efficient photovoltaic performance and ultra-thin form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fabrication methods are used on slim-type silicon substrates, then manufacturing simplicity is maintained, but photovoltaic efficiency and reliability deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing doping concentrations at different stages (initial doping at 800-900°C, phosphoric acid treatment concentration and time, aluminum paste composition ratios). These parameter adjustments enable high photovoltaic efficiency on slim-type substrates while using conventional fabrication equipment and processes, thus improving reliability without significantly increasing fabrication complexity
Solution Approach 2:
The patent implements preliminary action through the phosphoric acid treatment step performed before aluminum paste application. This preliminary etching and cleaning action prepares the surface of the slim-type substrate to enhance subsequent electrode adhesion and photovoltaic performance, achieving improved efficiency through an additional preparatory step rather than fundamentally changing the fabrication process
2Ease of operation
If slim-type silicon substrates are used, then device portability and handling are improved, but manufacturing precision and quality control deteriorate
Solution Approach 1:
The patent uses parameter changes by controlling the phosphoric acid concentration (0.1-10%) and treatment time (1-60 seconds) to achieve precise surface modification of slim-type substrates. This precise control of etching parameters ensures consistent electrode adhesion and photovoltaic performance across production batches, maintaining manufacturing precision while using lightweight substrates
Solution Approach 2:
The patent replaces mechanical anchoring methods with chemical bonding through phosphoric acid treatment. Instead of relying on mechanical interlocking of electrodes with the thin substrate, the chemical etching creates surface features and bonding sites that enhance adhesive strength, thereby maintaining quality control on slim-type substrates that are too thin for effective mechanical anchoring
3Reliability
If standard doping procedures are applied, then process simplicity is maintained, but photovoltaic performance deteriorates
Solution Approach 1:
The patent applies parameter changes by implementing a two-stage doping approach: initial doping at 800-900°C followed by phosphoric acid treatment at controlled concentrations and temperatures. This multi-parameter optimization of doping processes achieves superior photovoltaic efficiency with short-circuit current density of 35-40 mA/cm² and open-circuit voltage of 0.60-0.65 V, while the processes remain compatible with existing manufacturing equipment and procedures
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 method results in solar cells with enhanced short-circuit current, open-circuit voltage, and fill factor values, enabling high-efficiency silicon solar cells with selective emitters on slim-type silicon substrates processed at low temperatures, facilitating mass production and reduced costs.
Implementation Method 1
doping a silicon substrate having a first conductive type impurity with a second conductive type impurity
Implementation Method 2
a solar cell, which is a pollution-free energy source
Data Source
AI summary
A fabrication method of a solar cell, the method includes doping a silicon substrate having a first conductive type impurity with a second conductive type impurity, the second conductive type impurity being opposite to the first conductive type impurity, and thereby forming an emitter layer at a front surface part of the silicon substrate, forming an antireflection film on the emitter layer, forming a front electrode on the antireflection film, forming a rear electrode on a rear surface of the silicon substrate, and forming a back surface field layer at a rear surface part of the silicon substrate, the back surface field layer having a concentration of the first conductive type impurity that is higher than that of the silicon substrate, the back surface field layer having a different concentration of the second conductive type impurity from that of the emitter layer.