Doped Buffer Layer for CdTe Solar Cell Carrier Concentration
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Solution Overview
Problem
Current photovoltaic devices are inefficient due to low carrier concentration in cadmium telluride bulk, which can be improved by incorporating external dopants like copper into the back contact layer or doping the buffer layer.
Innovation Solution
A multilayered structure is created with a doped buffer layer adjacent to a transparent conductive oxide layer, where the dopant, such as copper, arsenic, or antimony, diffuses into the semiconductor absorber layer, increasing carrier concentration, and the structure includes a semiconductor window layer and absorber layer formed using materials like cadmium sulfide and cadmium telluride.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external dopants like copper are incorporated into the back contact layer or buffer layer is doped, then carrier concentration in cadmium telluride bulk is improved, but device complexity and manufacturing process complexity increase
Solution Approach 1:
The dopant is pre-incorporated into the buffer layer during the buffer layer formation process, before the absorber layer is deposited. This preliminary doping action eliminates the need for separate doping steps later in the process, reducing overall device complexity while achieving the desired carrier concentration improvement in the cadmium telluride bulk.
Solution Approach 2:
The buffer layer serves as an intermediary medium that facilitates dopant diffusion into the absorber layer. By placing the dopant in the buffer layer adjacent to the absorber layer, the buffer acts as a mediator that enables controlled dopant transfer during high-temperature processing, achieving bulk doping without direct contact doping methods.
2Reliability
If dopant diffusion is achieved through high-temperature processing, then carrier concentration increases, but energy consumption and processing time increase
Solution Approach 1:
The invention utilizes high-temperature processing conditions that are already present during absorber layer deposition or subsequent annealing steps. By leveraging these existing temperature parameters rather than introducing separate high-temperature doping steps, the method achieves dopant diffusion and carrier concentration improvement without additional energy consumption beyond what is already required for layer formation.
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 method enhances the open circuit voltage and carrier concentration of photovoltaic devices, improving their efficiency by diffusing dopants from the buffer layer into the absorber layer during high-temperature processing.
Implementation Method 1
the dopant, such as copper, arsenic, or antimony, diffuses into the semiconductor absorber layer, increasing carrier concentration
Data Source
AI summary
A multilayered structure may include a doped buffer layer on a transparent conductive oxide layer.