Thin-Film Solar Modules With TiN Barrier Layer
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Solution Overview
Problem
Existing photovoltaic thin-film solar modules face challenges in scalability, efficiency, and design flexibility due to complex multi-stage production processes, contamination issues, and high production costs, with limitations on module size and sensitivity to manufacturing conditions.
Innovation Solution
A photovoltaic thin-film solar module design featuring a substrate, molybdenum back electrode, conductive barrier layer, ohmic contact layer, semiconductor absorber layer, buffer layers, and a transparent front electrode, with structured separating trenches for series connection, and a method involving laser treatment and chemical phase transformation to reduce process steps and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a molybdenum rear electrode layer is used on a glass substrate, then good electrical conductivity and adhesion are achieved, but contamination and interdiffusion of components occur at elevated temperatures during production
Solution Approach 1:
A diffusion barrier layer made of titanium nitride (TiN) is introduced between the molybdenum rear electrode and the glass substrate. This intermediary layer prevents contamination and interdiffusion of components at elevated temperatures while maintaining good adhesion and electrical conductivity of the overall electrode structure.
2Reliability
If particularly pure rear electrode material is used, then efficiency is improved, but production costs increase disproportionately
Solution Approach 1:
The titanium nitride diffusion barrier layer acts as a protective intermediary that prevents contamination of the rear electrode material. This allows the use of cost-effective pureness materials without sacrificing efficiency, as the barrier layer protects against degradation during production and operation.
Solution Approach 2:
The invention changes the purity parameter requirement by introducing the barrier layer, which takes over the function of preventing contamination. This allows relaxation of material purity specifications while maintaining final product efficiency, thereby reducing production costs.
3Area of stationary object
If the module format exceeds 1.2 m x 0.5 m, then larger power output is achieved, but production becomes difficult or impossible due to plant technology limitations
Solution Approach 1:
The production process is segmented into distinct sequential steps: first depositing the glass substrate with rear electrode and diffusion barrier, then adding the semiconductor absorber layer, and finally applying the front electrode and encapsulation. This segmentation allows each step to be optimized independently and facilitates scaling to larger module formats beyond 1.2 m x 0.5 m.
4Reliability
If dopant is introduced into the semiconductor absorber layer, then efficiency is improved, but dopant diffuses into the back electrode and becomes depleted, reducing efficiency
Solution Approach 1:
The titanium nitride diffusion barrier layer serves as an intermediary that blocks dopant diffusion from the semiconductor absorber layer into the molybdenum back electrode. This prevents dopant depletion in the absorber layer, maintaining high efficiency while allowing beneficial dopant introduction.
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 solution enables the production of high-efficiency, flexible, and cost-effective thin-film solar modules with larger formats and improved adhesion, reduced contamination, and increased fill factor, while minimizing the impact of manufacturing conditions.
Implementation Method 1
removing the layers applied to the substrate layer along lines spaced apart from one another by means of laser treatment (first laser treatment) to form first structuring separating trenches
Implementation Method 2
chemical phase transformation and/or thermal decomposition of those layers that extend from the contact layer or from the rear electrode layer or from the barrier layer
Data Source
AI summary
The invention relates to photovoltaic thin-film solar modules, comprising in a first embodiment, particularly in the following order: at least one substrate layer; at least one rear electrode layer, particularly directly contacting the substrate layer; at least one conductive barrier layer, particularly directly contacting the rear electrode layer and/or the substrate layer; at least one contact layer, particularly an ohmic contact layer, particularly directly contacting the barrier layer; at least one semiconductor absorber layer, particularly a chalcopyrite or kesterite semiconductor absorber layer, particularly directly contacting the contact layer; optionally at least one first buffer layer, particularly directly contacting the semiconductor absorber layer and containing or substantially made of CdS or a CdS-free layer, particularly containing or made substantially of Zn(S, OH) or In2S3; and/or optionally at least one second buffer layer, particularly directly contacting the semiconductor absorber layer or the first buffer layer and containing or substantially made of intrinsic zinc oxide and/or high-resistance zinc oxide; and at least one transparent front electrode layer, particularly directly contacting the semiconductor absorber layer, the first buffer layer and/or the second buffer layer and particularly containing or substantially made of n-doped zinc oxide. Said thin-film solar modules further comprise: spaced-apart first structuring separation trenches filled with at least one insulating material, said trenches separating adjacent solar cells from one another down to the substrate layer; spaced-apart second structuring separation trenches filled or provided with at least one conductive material, said trenches extending to the contact layer or to the rear electrode layer or to the barrier layer, particularly to the barrier layer and each being adjacent to a filled first structuring separation trench; spaced-apart third structuring separation trenches, which extend to the contact layer or to the rear electrode layer or to the barrier layer, particularly to the barrier layer, and are each adjacent to a second structuring trench on the other side of the first structuring trench to which the second structuring trench is adjacent; and at least one conductive bridge from second structuring trenches filled with a conductive material or furnished with such a material to the front electrode layer of the adjacent solar cell, across adjacent first structuring separation trenches filled with insulating material. The invention further relates to a method for producing such thin-film solar modules.