Graded Absorber Layer for Flexible Thin-Film Photovoltaics
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Solution Overview
Problem
High-temperature deposition processes in thin-film photovoltaic device manufacturing restrict substrate material options, lead to contamination, and increase energy costs, while also limiting the use of flexible substrates and roll-to-roll production due to the need for high substrate temperatures and surface treatments.
Innovation Solution
A method involving a five-stage deposition process at temperatures between 350°C and 550°C, with specific atomic ratio adjustments and material flux rates, to create a graded absorber layer with improved crystalline structure and reduced impurity diffusion, allowing for high-efficiency photovoltaic devices on flexible substrates without the need for barrier layers or extensive surface treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-temperature deposition processes are used, then photovoltaic device efficiency is improved, but substrate material options are restricted and energy costs increase
Solution Approach 1:
The patent applies parameter changes by systematically varying deposition parameters including substrate temperature (reducing from conventional high temperatures to 350-550°C), deposition rate, atomic ratio of elements, and multi-stage deposition sequences to achieve high efficiency photovoltaic devices at lower temperatures
Solution Approach 2:
The patent implements local quality through compositional grading within the absorber layer, creating depth-dependent variations in element distribution (Cu, In, Ga, Se) to optimize local electronic properties and carrier collection efficiency, resulting in high device efficiency without requiring high substrate temperatures
2Manufacturing precision
If high-temperature deposition processes are used, then photovoltaic device efficiency is improved, but energy costs increase
Solution Approach 1:
The patent reduces energy consumption by changing the temperature parameter from conventional high temperatures to 350-550°C deposition range, while compensating for the reduced thermal energy through optimized deposition rates, atomic ratios, and multi-stage deposition processes that maintain high device efficiency
3Manufacturing precision
If high-temperature deposition processes are used, then photovoltaic device efficiency is improved, but contamination increases
Solution Approach 1:
The patent reduces contamination by lowering the substrate temperature parameter to 350-550°C, which minimizes thermal diffusion and impurity migration. The controlled low-temperature process prevents substrate material diffusion into the absorber layer and reduces oxidation, eliminating the need for barrier layers
4Manufacturing precision
If high-temperature deposition processes are used, then photovoltaic device efficiency is improved, but flexible substrate usage is restricted
Solution Approach 1:
The patent expands substrate material options by changing the temperature parameter to 350-550°C, which is compatible with flexible substrates such as plastic foils that cannot withstand high temperatures. This enables deposition on diverse substrates including glass, metal foils, and flexible plastics
5Manufacturing precision
If high-temperature deposition processes are used, then photovoltaic device efficiency is improved, but surface treatments are required
Solution Approach 1:
The patent eliminates surface treatment requirements by optimizing the deposition parameter of substrate temperature to 350-550°C, which enables direct deposition of high-quality absorber layers without the need for barrier layers or extensive surface treatments, simplifying the manufacturing process
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 method enables the production of high-efficiency photovoltaic devices with improved crystalline structure and reduced recombination, achieving efficiencies comparable to silicon wafer-based devices while using flexible substrates and enabling low-cost, low-energy roll-to-roll production.
Implementation Method 1
deposition of semiconductor material as a thin film onto a substrate
Data Source
Figure 1~2C
Figure 3A~3C
Figure 4A~4B
AI summary
A thin-film photovoltaic device (100) comprising a flexible substrate (110) and an absorber layer (130), wherein said absorber layer (130) is made of an ABC chalcogenide material, including ABC chalcogenide material quaternary, pentanary, or multinary variations, wherein A represents elements in group 11 of the periodic table of chemical elements as defined by the International Union of Pure and Applied Chemistry including Cu and Ag, B represents elements in group 13 of the periodic table including In, Ga and Al, and C represents elements in group 16 of the periodic table including S, Se and Te, wherein said ABC chalcogenide material comprises In and Ga elements, characterized in that a compositional analysis of smoothed Ga / (Ga + In) ratio data across the thickness of said absorber layer forms a Ga / (Ga + In) ratio curve (500) in which, starting from a light-exposed side of said absorber layer, said Ga / (Ga + In) ratio curve (500) comprises at least two regions (501, 502) comprising: a. a front grading region (501) of decreasing Ga / (Ga + In) ratio where a light-exposed side of said front grading region has a Ga / (Ga + In) value that is less than 0.5 and where the amplitude of the Ga / (Ga + In) value in said front grading region is less than 0.25 and greater than 0.1; b. a back grading region (502), adjacent to said front grading region (501) and located between said front grading region (501) and the back side of the absorber layer opposite the light-exposed side, of overall increasing Ga / (Ga + In) ratio where: i. over the light-exposed half side of said back grading region (502) the value of Ga / (Ga + In) increases by less than 0.20.