Photocatalytic Semiconductor Buffer Layer Deposition
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Solution Overview
Problem
Current methods for depositing thin semiconductor buffer layers in solar cells, such as chemical bath deposition (CBD) and electrochemical deposition, face issues like carcinogenic precursors, volatile complexing agents, energy inefficiency, and complex equipment requirements, leading to imprecise control and high waste generation.
Innovation Solution
A photocatalytic method using a chemical bath with thioacids as sulfur precursors, where the thin layer is formed by illuminating the bath and semiconductor film without heating or electric potential, allowing for simpler, energy-efficient, and carcinogen-free deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical bath deposition with thioamides or thiourea is used, then buffer layers can be formed, but the precursors are carcinogenic or suspected to be carcinogenic
Solution Approach 1:
The patent replaces carcinogenic thioamides and thiourea with thioacids (R-COSH) as sulfur precursors. Thioacids are non-carcinogenic, biodegradable compounds that fulfill the same functional role in buffer layer formation, eliminating the harmful effects while maintaining deposition reliability
Solution Approach 2:
The invention changes the chemical parameters of the precursor compounds from carcinogenic thioamides/thiourea to non-carcinogenic thioacids. This parameter change in the chemical composition eliminates carcinogenicity while preserving the ability to form high-quality buffer layers through photocatalytic deposition
2Reliability
If the chemical bath is heated for deposition, then the buffer layer grows, but energy consumption increases significantly
Solution Approach 1:
The patent replaces thermal energy input (heating) with optical energy input (illumination). By using light sources to drive photocatalytic reactions, the deposition process achieves buffer layer growth without significant heating, dramatically reducing energy consumption while maintaining reliable layer formation
Solution Approach 2:
The invention utilizes photocatalytic phase transitions driven by light absorption. The light source provides energy to initiate and sustain the chemical reactions needed for buffer layer growth, replacing the need for thermal energy and associated heating processes
3Manufacturing precision
If ammonia is used as a complexing agent in the chemical bath, then deposition can be controlled, but ammonia evaporates when heated causing imprecise control
Solution Approach 1:
The patent eliminates ammonia as a complexing agent by using thioacids as the primary sulfur source. This removal of volatile ammonia prevents evaporation losses and the associated loss of deposition control precision, while thioacids provide stable and controllable deposition conditions
Solution Approach 2:
The invention changes the chemical composition parameters by replacing volatile ammonia with non-volatile thioacids. This parameter change eliminates evaporation issues and improves deposition control precision, as thioacids remain stable in the chemical bath without significant loss to the atmosphere
4Reliability
If electrochemical deposition is used, then buffer layers can be formed, but expensive equipment and deoxygenation processes are required
Solution Approach 1:
The patent extracts and eliminates the need for complex electrochemical equipment by using photocatalytic deposition. This simpler method forms buffer layers using only a chemical bath and light source, removing expensive electrodes, power supplies, and deoxygenation systems while maintaining reliable deposition
Solution Approach 2:
The invention replaces the electrochemical system (electrodes, power supplies, potential difference application) with a photocatalytic system (light source, chemical bath). This substitution dramatically simplifies the equipment while maintaining the ability to form high-quality buffer layers
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 formation of high-quality thin semiconductor layers with improved control and reduced energy consumption, avoiding carcinogenic compounds and equipment complexity, while enhancing solar cell efficiency and reducing waste.
Implementation Method 1
form the thin film by illuminating the chemical bath and the semiconductor film by means of a light source
Implementation Method 2
forming the thin film by illuminating the chemical bath and the semiconductor film by means of a light source
Data Source
Figure 1a~2
Figure 3~4
Figure 5a~5b
AI summary
The invention relates to a method for depositing a semiconductor thin layer (CM) comprising at least one sulphide of a metal species, the deposition being performed on a semiconductor film (F) arranged in a chemical bath (BC), the method comprising the steps of: preparing the chemical bath (BC) using at least one sulphurated precursor of said sulphide of a metal species and a salt containing said at least one metal species, the at least one sulphurated precursor containing a thioacid; and forming the thin layer (CM) by illumination by means of a light source (S) of the chemical bath (BC) and the semi-conductive film (F).