Porous Passivated Contact Structures for Lower Solar-Cell Recombination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional interdigitated back contact (IBC) solar cells face issues such as poor isolation effect, increased recombination, reduced conversion efficiency due to direct contact with the silicon substrate, and scratches during belt transportation, which affect production scalability and efficiency.
Innovation Solution
A passivated contact structure with a porous first passivation layer and a second passivation layer, featuring nano-level holes and openings for conductive layer connection, enhances isolation and reduces recombination, while a back contact structure with a protective region prevents scratches during transportation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tunneling layer is used to isolate doped polysilicon from silicon substrate, then passivation effect is improved, but manufacturing precision is worsened due to difficulty in controlling thickness accuracy
Solution Approach 1:
The patent introduces a dielectric layer as an intermediary between the doped polysilicon and the silicon substrate. This dielectric layer serves as a protective barrier that prevents direct contact and harmful interactions, while also providing electrical insulation. The dielectric layer can be formed with controlled thickness through standard deposition processes, avoiding the thickness control difficulties associated with tunneling layers.
Solution Approach 2:
The patent changes the material parameter from a tunneling layer (which requires precise thickness control) to a dielectric layer (which can be formed with broader thickness tolerance). This parameter change allows for easier manufacturing while maintaining the isolation and passivation functions. The dielectric layer's electrical properties can be adjusted by changing material composition rather than relying solely on precise thickness control.
2Ease of manufacture
If doped polysilicon is directly printed in P region or N region, then electrode connection is simplified, but burn-through occurs during sintering causing direct contact with silicon substrate and increased recombination
Solution Approach 1:
The dielectric layer acts as a protective intermediary between the conductive paste and the doped polysilicon. During the sintering process, this dielectric layer prevents the conductive paste from burning through to the silicon substrate, thereby avoiding direct contact and the associated recombination losses. The dielectric layer maintains electrical connectivity while providing thermal and mechanical protection.
Solution Approach 2:
The dielectric layer is formed beforehand as a protective cushioning layer between the conductive paste and the sensitive doped polysilicon structure. This prior cushioning prevents damage during subsequent sintering operations, protecting the underlying structure from thermal and mechanical stress that could cause burn-through and direct substrate contact.
3Power
If conventional IBC cell structure is used, then conversion efficiency is improved through wider electrode design, but production scalability is worsened due to multiple processes and transportation requirements
Solution Approach 1:
The patent merges multiple separate processes into a more integrated approach. The dielectric layer is formed as part of the standard fabrication sequence, eliminating the need for separate protective layer deposition and subsequent removal steps. This consolidation reduces the number of process transitions and transportation operations required, thereby improving production scalability while maintaining high conversion efficiency.
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 improves isolation, reduces recombination, and prevents scratches, leading to enhanced conversion efficiency and reduced surface pollution, with flexible thickness control and cost-effective fabrication.
Implementation Method 1
a first passivation layer, disposed on the silicon substrate, having a porous structure with a hole region, and a second passivation layer, disposed on the first passivation layer
Implementation Method 2
the passivation effect is poor, and a surface is prone to pollution
Data Source
AI summary
A solar cell includes a silicon substrate, a first doped region, and a second doped region. The first doped region includes a first passivated contact region on the silicon substrate and a second passivated contact region on the first passivated contact region. The first passivated contact region includes a first doped layer, a first passivation layer, and a second doped layer. The second passivated contact region includes a second passivation layer and a third doped layer. The second doped region includes a third passivation layer. Each of the first and third passivation layers includes a porous structure. One of the first and second doped regions is a P-type doped region, the other of the first and second doped regions is an N-type doped region, and a hole density of a corresponding passivation layer in the P-type doped region is greater than that in the N-type doped region.