Solar Cell Retardation Layer for Ion Migration and Recombination Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Recombination loss at the metal contact area in solar cells hinders the improvement of conversion efficiency, as existing passivated contact cells face challenges in reducing recombination losses effectively.
Innovation Solution
A solar cell structure is designed with a retardation layer comprising overlapping and misaligned sub-layers, where the second sub-layer is an intrinsic semiconductor, to retard the migration of doped ions and maintain a selective carrier transmission, thereby reducing recombination loss and enhancing conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a passivated contact is applied to reduce recombination loss, then conversion efficiency is improved, but doped ion migration to the substrate occurs causing recombination loss
Solution Approach 1:
An intrinsic semiconductor layer is introduced as an intermediary between the doped semiconductor layer and the substrate. This intermediate layer prevents direct contact and migration pathways for doped ions while maintaining the passivation function, thereby resolving the contradiction between reducing recombination loss and controlling ion migration.
Solution Approach 2:
The passivated contact structure is segmented into multiple functional layers: a doped semiconductor layer for carrier selectivity, an intrinsic semiconductor layer for ion migration barrier, and a passivation layer for surface passivation. This segmentation allows each layer to perform its specific function optimally without interfering with others.
2Reliability
If the retardation layer thickness is increased to prevent ion migration, then ion migration is reduced, but majority carrier transmission is hindered
Solution Approach 1:
The thickness of the intrinsic semiconductor layer is precisely controlled within a specific range (0.1-5 μm) to achieve optimal performance. This parameter optimization ensures the layer is thick enough to prevent ion migration during thermal processing while remaining thin enough to allow efficient majority carrier transmission through the passivated contact.
3Reliability
If the distance between field passivation layer and substrate is increased to reduce ion migration, then ion migration is reduced, but band bending effect is weakened
Solution Approach 1:
The intrinsic semiconductor layer acts as a mediator that physically separates the field passivation layer from the substrate, preventing ion migration pathways. This intermediate structure allows the field passivation layer to maintain its position and band bending effect while the intrinsic layer blocks ion transport to the substrate.
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 structure ensures a large potential barrier between the field passivation layer and the substrate, maintaining effective carrier transmission and improving open circuit voltage and conversion efficiency by diluting doping concentrations and enhancing band bending effects.
Implementation Method 1
a tunneling layer, a retardation layer, a field passivation layer, a second passivation film and a second electrode that are sequentially disposed on a lower surface of the substrate
Implementation Method 2
maintaining a selective transmission of the carrier, and improving an open circuit voltage and a conversion efficiency of the solar cell
Implementation Method 3
The retardation layer is configured to retard a migration of a doped ion in the field passivation layer to the substrate
Data Source
AI summary
Disclosed is a solar cell, including: a substrate; an emitter, a first passivation film, an antireflection film and a first electrode sequentially disposed on an upper surface of the substrate; a tunneling layer, a retardation layer, a field passivation layer, a second passivation film and a second electrode sequentially disposed on a lower surface of the substrate. The retardation layer is configured to retard a migration of a doped ion in the field passivation layer to the substrate. The retardation layer includes a first retardation sub-layer overlapping with a projection of the second electrode and a second retardation sub-layer misaligning with a projection of the second electrode, and at least the second retardation sub-layer is an intrinsic semiconductor. A thickness of the first retardation sub-layer is smaller than a thickness of the second retardation sub-layer in a direction perpendicular to the surface of the substrate.