3D Porous CZTS Solar Cell with N-Type Buffer Layer
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Solution Overview
Problem
Conventional CZTS thin film solar cells face challenges in achieving high photoelectric conversion efficiency due to limitations in carrier diffusion length and morphology, particularly when produced using non-vacuum processes that require organic binders, leading to increased costs and carbon residue issues.
Innovation Solution
A 3-dimensional P-N junction solar cell is developed with a 3-dimensional porous P-type semiconductor thin film and a N-type buffer layer, using a CZTS precursor solution coated and heated in the presence of sulfur or selenium, eliminating the need for organic binders and allowing for control of morphology and porosity, thereby enhancing carrier delivery and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If non-vacuum process with organic binder is used to produce CZTS thin film, then production cost is reduced, but carbon residue problem occurs and morphology is limited
Solution Approach 1:
The invention extracts and removes the organic binder component from the precursor solution formulation, replacing it with an inorganic-based system that eliminates carbon residue formation while maintaining the low-cost non-vacuum processing advantage
Solution Approach 2:
The invention changes the chemical composition parameters of the precursor solution by eliminating organic binding agents and using inorganic salts and chelating agents instead, fundamentally altering the decomposition behavior during heating to prevent carbon residue
2Device complexity
If conventional thin film structure is used, then manufacturing is simple, but carrier diffusion length is limited and efficiency is reduced
Solution Approach 1:
The invention transitions from a conventional two-dimensional planar thin film structure to a three-dimensional hierarchical porous structure with vertical and lateral dimensions optimized for carrier transport, dramatically increasing the effective surface area and carrier diffusion pathways without complicating the manufacturing process
3Manufacturing precision
If vacuum process is used to produce CZTS thin film, then chemical composition control is improved, but production cost increases
Solution Approach 1:
The invention replaces the vacuum-based physical deposition system with a solution-based chemical deposition system that operates at atmospheric pressure, using solution chemistry to control composition rather than vacuum physics, thereby eliminating expensive equipment requirements while maintaining precise compositional control through solution formulation
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 results in improved photoelectric conversion efficiency, reduced production costs, and simplified manufacturing processes, enabling the production of high-quality solar cells with controlled properties through a non-vacuum process.
Implementation Method 1
heating the pre-heated thin film at 500 ̃600° C. in the presence of one or more gases selected from the group consisting of sulfur and selenium
Implementation Method 2
forming a 3-dimensional porous P type semiconductor thin film on top of the base board coated with the back plate
Implementation Method 3
a N type buffer layer formed on the surface of the crystal grains of the P type semiconductor thin film with playing a role of coating the thin film
Implementation Method 4
Once exposed on a strong light, electrons and positive holes are excited and move freely in the semiconductor, and then the electrons and positive holes move to each electrode by P-N junction to generate electric current
Data Source
AI summary
The present invention provides a 3-dimensional P-N junction solar cell composed of a base board coated with a back plate on the upper face of the same; a P type semiconductor thin film formed on the top side of the back plate which has a 3-dimensional porous structure and is composed of P type semiconductor crystal grains; a N type buffer layer formed on the surface of the crystal grains of the said P type semiconductor thin film with playing a role of coating the thin film; and a transparent electrode formed on the surface of the crystal grains of the P type semiconductor thin film on which the N type buffer layer is formed. The solar cell of the present invention is a P-N junction solar cell including a 3-dimensional photo catalytic thin film, which can provide an improved photoelectric conversion efficiency, compared with the conventional P-N junction solar cell, owing to the formation of the N-type buffer layer on the surface of the crystal grains of the 3-dimensional P type semiconductor thin film.