Conductive Barrier Layer for Thin Film Solar Modules
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Solution Overview
Problem
The production of photovoltaic thin-film solar modules faces challenges such as contamination, interdiffusion of components, and limitations in module size due to complex multi-stage processes and interactions, which restrict scalability and efficiency.
Innovation Solution
A method involving a bidirectionally acting conductive barrier layer, preferably made of metal nitrides like TiN, is used to prevent diffusion of dopants and impurities, allowing for a reduced semiconductor absorber layer thickness and enabling larger module formats by controlling alkali ion accumulation and dopant distribution, while maintaining high efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex multi-stage process is used to produce thin-film solar modules, then the module efficiency can be maintained, but contamination and interdiffusion of components occur, worsening manufacturing precision
Solution Approach 1:
A conductive barrier layer is introduced as an intermediary between the rear electrode and the semiconductor absorber layer. This barrier layer prevents diffusion of dopants and impurities from the rear electrode into the semiconductor layer, while maintaining electrical conductivity to allow charge carrier extraction. The barrier layer thus mediates between the conflicting requirements of electrical conductivity and diffusion prevention, eliminating contamination issues without compromising module efficiency.
2Reliability
If traditional rear electrode structures are used, then alkali ion accumulation occurs at the interface, but a bidirectionally acting conductive barrier layer prevents this accumulation while maintaining dopant distribution
Solution Approach 1:
The conductive barrier layer serves as a mediator that selectively blocks alkali ions from accumulating at the electrode-semiconductor interface while allowing dopants to distribute properly in the semiconductor layer. This intermediary structure prevents adhesion problems caused by alkali ion accumulation without interfering with the necessary dopant distribution for maintaining semiconductor functionality and efficiency.
3Reliability
If the semiconductor absorber layer thickness is reduced to improve efficiency, then light absorption is enhanced, but dopant depletion occurs without a barrier layer
Solution Approach 1:
The conductive barrier layer acts as a protective intermediary between the rear electrode and the thinned semiconductor absorber layer. It prevents dopant depletion by blocking the diffusion path from the electrode into the semiconductor, enabling the use of reduced thickness semiconductor layers that enhance light absorption efficiency without suffering from dopant loss to the electrode.
4Productivity
If module format is increased beyond 1.2m x 0.5m for scalability, then production scale is improved, but plant technology cannot prevent contamination and interdiffusion
Solution Approach 1:
The conductive barrier layer provides a reliable diffusion barrier that maintains layer purity control even in large-format modules produced in plant technology settings. By preventing interdiffusion of components between layers, the barrier layer enables manufacturing of scaled-up modules beyond 1.2m x 0.5m while maintaining the manufacturing precision and component purity required for efficient solar cell operation.
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 approach reduces contamination, allows for larger module formats, and enhances efficiency by preventing dopant depletion and adhesion issues, enabling reproducibly high efficiencies and cost-effective mass production of monolithically integrated series-connected solar cells.
Implementation Method 1
A bidirectionally acting conductive barrier layer, preferably made of metal nitrides like TiN, is used to prevent diffusion of dopants and impurities
Implementation Method 2
controlling alkali ion accumulation and dopant distribution
Data Source
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AI summary
The present invention relates to a method for producing photovoltaic thin-film solar modules, comprising the steps of: - applying a back electrode layer on a substrate, - applying at least a conductive barrier layer, - applying at least one contact layer, - applying at least one kesterite or chalcopyrite semiconductor absorber layer, - applying at least a buffer layer, - removing the applied layers by means of laser treatment with the formation of first separating trenches, - filling the first separating trenches with at least one insulating material, - removing those layers which extend from the barrier layer in the direction of the semiconductor absorber layer with the formation of second separating trenches, or chemical phase conversion or thermal decomposition of those layers which extend from the barrier layer in the direction of the semiconductor absorber layer with the formation of first linear conductive areas, - applying at least one transparent front electrode layer by filling and contacting the second separating trenches or by contacting the first linear conductive areas, so that adjacent solar cells are connected in series, - removing the layers which extend from the barrier layer in the direction of the front electrode layer with the formation of third separating trenches. The invention further relates to the photovoltaic thin-film solar modules which are obtained by the method according to the invention.