Multi-Cell Photovoltaic Devices Without Physical Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for fabricating multi-cell photovoltaic devices on a common substrate require physical isolation between cells, which increases fabrication complexity and cost due to the need for epitaxial layers and trench formation.
Innovation Solution
The solution involves forming interdigitated P-N junction cells without physical isolation, using diffusion fields to electrically isolate individual cells by orienting the diffusion fields transverse to the current flow, thereby eliminating the need for epitaxial layers and trench isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical isolation barriers (trenches) are used between cells, then electrical isolation between cells is achieved, but fabrication complexity and cost increase due to multiple epitaxial layers and trench formation
Solution Approach 1:
The invention extracts and eliminates the physical isolation barriers (trenches and dielectric layers) from the multi-cell device structure. By removing these unnecessary isolation elements, the patent achieves electrical isolation through the inherent properties of the semiconductor material and device geometry alone, thereby simplifying fabrication processes and reducing manufacturing complexity while maintaining reliable electrical isolation between cells
Solution Approach 2:
The invention introduces a potential well structure as an intermediary element that provides electrical isolation between adjacent photovoltaic cells. This potential well acts as a mediator that prevents carrier diffusion between cells without requiring physical trenches or complex epitaxial layering, thus achieving isolation with simpler fabrication
2Reliability
If physical trenches are formed for isolation, then electrical isolation is achieved, but processing costs increase beyond trench fabrication cost
Solution Approach 1:
The invention merges the isolation function with the active semiconductor structure by using the potential well and intrinsic semiconductor regions to provide both carrier collection functionality and electrical isolation. This consolidation eliminates the need for separate isolation structures and multiple epitaxial layers, reducing processing costs while maintaining effective electrical isolation between cells
3Reliability
If multiple epitaxial layers are incorporated for trench fabrication, then electrical isolation is achieved, but fabrication requirements become complex requiring highly skilled technologists
Solution Approach 1:
The invention extracts and eliminates the requirement for multiple complex epitaxial layers from the fabrication process. By using a simplified structure with intrinsic semiconductor regions and potential wells formed through standard diffusion or implantation processes, the patent reduces fabrication requirements to levels achievable with常规 manufacturing capabilities, eliminating the need for highly specialized epitaxial growth expertise
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 reduces fabrication complexity and cost, achieving electrical isolation equivalent to physical isolation while minimizing parasitic currents, allowing for efficient photocurrent generation and voltage accumulation across the multi-cell device.
Implementation Method 1
Each individual P-N junction cell includes an absorption region and a diffusion field between the P-type and N-type material that forms as a result of the holes and electrons created by the absorption of photons and the concentration gradient that results from their collection by the P and N regions
Implementation Method 2
Each individual P-N junction cell includes an absorption region and a diffusion field between the P-type and N-type material that forms as a result of the holes and electrons created by the absorption of photons
Implementation Method 3
The holes and electrons are collected by ohmic contacts on the P-type and N-type material and result in an output photocurrent and a forward bias voltage across the P-N junction cell
Data Source
AI summary
The present invention relates to multi-cell devices fabricated on a common substrate that are more desirable than single cell devices, particularly in photovoltaic applications. Multi-cell devices operate with lower currents, higher output voltages, and lower internal power losses. Prior art multi-cell devices use physical isolation to achieve electrical isolation between cells. In order to fabricate a multicell device on a common substrate, the individual cells must be electrically isolated from one another. In the prior art, isolation generally required creating a physical dielectric barrier between the cells, which adds complexity and cost to the fabrication process. The disclosed invention achieves electrical isolation without physical isolation by proper orientation of interdigitated junctions such that the diffusion fields present in the interdigitated region essentially prevent the formation of a significant parasitic current which would be in opposition to the output of the device.