Copper-Free CdTe Thin-Film Solar Cell Doping With X-Halogen Annealing
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Solution Overview
Problem
Copper doping in CdTe based thin film solar cell devices results in low device stability and charge carrier lifetime, necessitating an alternative doping method for improved photovoltaic efficiency.
Innovation Solution
A method involving ex-situ doping of CdTe based thin film solar cells with X-halogen (P, As, Sb, or V) followed by a thermal treatment at controlled temperatures and atmospheres, without copper, to enhance doping efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If copper is used as doping element in CdTe based thin film solar cell devices, then manufacturing process is simple and well-established, but device stability and charge carrier lifetime are reduced
Solution Approach 1:
The patent changes the doping element from copper to alternative elements (P, As, Sb, Bi) and adjusts the doping process parameters including temperature (40-120°C), time (10-60 minutes), and atmosphere (inert or vacuum) to achieve both manufacturability and improved device stability without copper
Solution Approach 2:
The patent employs alternative doping elements (P, As, Sb, Bi) that can be introduced through simple ex-situ doping processes using common laboratory equipment, replacing copper while maintaining ease of manufacture and improving reliability
2Ease of manufacture
If copper is used as doping element in CdTe based thin film solar cell devices, then manufacturing process is straightforward, but charge carrier lifetime is reduced
Solution Approach 1:
The patent changes the doping element from copper to alternative elements (P, As, Sb, Bi) and optimizes process parameters including lower temperatures (40-120°C) and controlled atmosphere to extend charge carrier lifetime while maintaining manufacturing simplicity
3Reliability
If ex-situ doping with X-halogen is performed, then copper-free doping is achieved, but additional thermal treatment step is required
Solution Approach 1:
The patent specifies precise thermal treatment parameters (40-120°C, 10-60 minutes, inert atmosphere or vacuum) that enable effective doping without copper while the added thermal treatment step is optimized to minimize overall process complexity
Solution Approach 2:
The patent employs inert atmosphere or vacuum during thermal treatment to prevent oxidation and other unwanted reactions, enabling reliable copper-free doping while the controlled environment simplifies the overall process by preventing side reactions
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 copper-free CdTe based thin film solar cells with improved photovoltaic efficiency and stability by optimizing the doping process.
Implementation Method 1
Performing a thermal treatment after step d), wherein the thermal treatment in step e) is performed before step f) and at a temperature in the range of 40° C. to 120° C. in an inert atmosphere or vacuum for a duration in the range of 10 minutes to 60 minutes
Implementation Method 2
Applying a X-halogen to the CdTe based absorber layer, wherein X is selected out of a group consisting of P, As, Sb and V, followed by performing a thermal treatment
Data Source
AI summary
A method for manufacturing a copper-free CdTe based thin film solar cell device, comprising the following steps: a) providing a substrate at least comprising a front electrode, b) depositing a CdTe based absorber layer, c) performing an activation treatment, d) applying a X-halogen to the CdTe based absorber layer, wherein X is selected out of a group consisting of P, As, Sb and V; e) performing a thermal treatment after step d) and f) depositing a back contact, characterized in that, the thermal treatment in step e) is performed before step f) and at temperatures in the range of 40° C. to 120° C. in inert atmosphere or vacuum for a duration in the range of 10 minutes to 60 minutes.