Photovoltaic Passivation Layer Gradient Doping for Contact Resistance
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Solution Overview
Problem
The abrupt change in doping element concentration in the passivation layer of photovoltaic cells leads to reduced passivation effect and photoelectric conversion efficiency due to increased carrier recombination and contact resistance between the electrode and substrate.
Innovation Solution
A photovoltaic cell design with a passivation layer comprising interleaved first and second portions, where the doping concentration gradually decreases from the second portion towards the first portion, reducing potential barriers and contact resistance, and increasing the doping concentration towards the electrode, facilitating carrier transmission and reducing light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high doping concentration is used in the passivation layer to improve ohmic contact between electrode and substrate, then contact resistance is reduced, but light absorption increases reducing photoelectric conversion efficiency
Solution Approach 1:
The passivation layer is divided into two distinct regions with different doping concentrations: a first portion with high doping concentration (1×10^21 to 5×10^21 atoms/cm³) positioned at the electrode contact area to ensure low contact resistance and good ohmic contact, and a second portion with low doping concentration (1×10^19 to 1×10^20 atoms/cm³) positioned in the light incident area to minimize light absorption and maximize photoelectric conversion efficiency
Solution Approach 2:
The passivation layer is segmented into functionally distinct first and second portions along the direction perpendicular to the substrate surface, allowing independent optimization of doping concentrations for each functional region - the first portion for electrical contact performance and the second portion for optical performance
2Productivity
If a low doping concentration is used in the passivation layer to reduce light absorption and improve photoelectric conversion efficiency, then light absorption is reduced, but contact resistance increases reducing electrode-substrate interface quality
Solution Approach 1:
The passivation layer is divided into two distinct regions with different doping concentrations: a first portion with high doping concentration (1×10^21 to 5×10^21 atoms/cm³) positioned at the electrode contact area to ensure low contact resistance and good ohmic contact, and a second portion with low doping concentration (1×10^19 to 1×10^20 atoms/cm³) positioned in the light incident area to minimize light absorption and maximize photoelectric conversion efficiency
Solution Approach 2:
The passivation layer is segmented into functionally distinct first and second portions along the direction perpendicular to the substrate surface, allowing independent optimization of doping concentrations for each functional region - the first portion for electrical contact performance and the second portion for optical performance
3Productivity
If an abrupt change in doping element concentration is created in the passivation layer to achieve high doping near electrode and low doping in illuminated portion, then doping concentration distribution is optimized, but potential difference becomes abrupt affecting passivation effect
Solution Approach 1:
The doping concentration parameter is changed spatially across the passivation layer thickness, transitioning from high concentration (1×10^21 to 5×10^21 atoms/cm³) in the first portion near the electrode to low concentration (1×10^19 to 1×10^20 atoms/cm³) in the second portion in the light incident area, optimizing both electrical and optical performance
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 design enhances the passivation effect, prolongs minority carrier lifetime, increases open circuit voltage and saturation current, and improves photoelectric conversion efficiency by reducing composite current density and light absorption.
Implementation Method 1
increasing the doping concentration towards the electrode, facilitating carrier transmission
Implementation Method 2
Photovoltaic cells are semiconductor devices that convert solar energy into electrical energy
Data Source
AI summary
A photovoltaic cell is provided, including a substrate and a passivation layer on the substrate. The passivation layer includes first portions and second portions interleaved with each other in a direction perpendicular to a normal of the first surface of the substrate. The first and second portions are doped with a same type of doping elements, each second portion has a reference surface away from the substrate, a doping concentration of doping elements in a second portion gradually decreases in a direction from a center of the reference surface toward an adjacent first portion and in a direction from the center of the reference surface toward the substrate, and a doping concentration of doping elements in the first portion is less than or equal to a minimum doping concentration of doping elements in the second portion.