Back-Contact MIS Solar Cell With Printed Oxide Tunnel Junctions
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Solution Overview
Problem
The fabrication of interdigitated back-contact silicon solar cells is complex and costly, limiting the efficiency and cost-effectiveness of silicon solar cells, as existing methods require intricate masking and etching techniques that are not compatible with high-volume, low-cost manufacturing.
Innovation Solution
A method involving screen-printing of positively and negatively charged oxide tunnel junctions on the back surface of silicon substrates, followed by the application of metallic glass-coated electrodes, which eliminates the need for costly masking and etching processes, enabling the formation of metal-insulator-semiconductor (MIS) solar cells with interdigitated back surface contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional fabrication processes with front-side metallization grid and back-side aluminum back-surface field are used, then manufacturing complexity and cost are reduced, but solar cell efficiency is limited due to front-side contacts blocking incident solar radiation
Solution Approach 1:
The patent inverts the conventional solar cell architecture by moving all electrical contacts from the front surface to the back surface. This interdigitated back-contact design eliminates front-side metallization that blocks solar radiation, allowing the entire top surface to absorb incident light. The inversion resolves the contradiction by prioritizing energy absorption over manufacturing simplicity, using screen-printable pastes to achieve the complex back-contact structure.
Solution Approach 2:
The patent transitions from a planar front-side contact configuration to a three-dimensional back-contact architecture. By depositing oxide tunnel junctions and metal contacts on the back surface in interdigitated regions, the design utilizes the vertical dimension and back surface area to achieve both high efficiency and electrical functionality, resolving the conflict between energy loss and device complexity.
2Loss of energy
If interdigitated back-contact solar cells are fabricated using intricate masking and etching techniques, then solar cell efficiency is improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent replaces complex mechanical masking and etching processes with a screen-printing-based deposition system. Screen-printable metallization pastes containing oxide precursors are deposited through screens onto the back surface, followed by thermal processing to form the oxide tunnel junctions and metal contacts. This substitution eliminates the need for intricate masking and etching, significantly reducing manufacturing complexity and cost while maintaining high efficiency.
Solution Approach 2:
The patent changes the physical and chemical parameters of the deposition process by using screen-printable pastes that decompose thermally to form oxide layers. By controlling the paste composition, screen mesh size, and thermal processing parameters, the complex interdigitated structure is formed through a simplified single-step deposition process rather than multiple masking and etching steps, improving ease of manufacture.
3Ease of manufacture
If screen-printable metallization pastes are used to form oxide tunnel junctions on back surface, then manufacturing simplicity and cost are improved, but achieving ultra-thin oxide layers with proper charge requires precise process control
Solution Approach 1:
The patent controls oxide layer thickness and charge by adjusting paste composition (oxide precursor content, particle size distribution), screen printing parameters (screen mesh size, printing pressure, paste deposition rate), and thermal processing conditions (heating temperature, time, atmosphere). These parameter changes enable precise control of the oxide layer properties while maintaining the simplicity of screen printing, resolving the contradiction between ease of manufacture and manufacturing precision.
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 approach simplifies the fabrication process, reduces material costs, and enhances the efficiency of silicon solar cells by allowing for the formation of ultra-thin oxide dielectric layers and electrodes compatible with high-volume manufacturing, while maintaining the reliability and conductivity of the solar cells.
Implementation Method 1
interdigitated back contact metal-insulator-semiconductor solar cell
Implementation Method 2
oxide tunnel junctions
Data Source
AI summary
Screen-printable metallization pastes for forming thin oxide tunnel junctions on the back-side surface of solar cells are disclosed. Interdigitated metal contacts can be deposited on the oxide tunnel junctions to provide all-back metal contact to a solar cell.