Multi-junction Solar Cell Tunnel Junction Lattice Mismatch
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multi-junction solar cells face inefficiencies due to mismatched lattice structures and surface recombination issues between silicon and germanium solar cells, which affect energy conversion efficiency and photocurrent production.
Innovation Solution
A multi-junction solar cell configuration is developed, featuring a high-crystalline silicon solar cell and a high-crystalline germanium solar cell with a tunnel junction between them, along with doped layers and back surface fields to minimize electrical and optical losses and enhance energy absorption across a broader wavelength range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple solar cells with different semiconductor materials are stacked to absorb broader wavelengths, then energy conversion efficiency is improved, but lattice structure mismatch and surface recombination issues arise
Solution Approach 1:
The patent introduces an intermediary layer between the silicon and germanium solar cells to mediate the lattice structure mismatch. This intermediate structure acts as a buffer that accommodates the crystallographic differences between the two materials, preventing dislocation and maintaining structural integrity while allowing the multi-junction configuration to function effectively
Solution Approach 2:
The patent modifies the surface properties of the solar cell interfaces through doping and field effect engineering. By changing the electrical parameters (carrier concentration, field distribution) at the interfaces, the patent reduces surface recombination losses and optimizes charge carrier collection, thereby resolving the reliability issue associated with material interfaces
2Productivity
If multiple solar cells with different semiconductor materials are stacked to absorb broader wavelengths, then energy conversion efficiency is improved, but surface recombination losses increase
Solution Approach 1:
The patent changes the electrical parameters at the surfaces and interfaces by introducing doped layers and back surface fields. These parameter modifications create potential barriers that prevent carrier recombination at surfaces, reducing energy loss while maintaining the optical absorption benefits of the multi-junction structure
Solution Approach 2:
The patent applies preliminary protective measures at the surfaces through doping and field effect structures before carriers can recombine. These pre-established electrical fields and concentration gradients act in advance to repel carriers from high-recombination surfaces, preventing energy loss before it occurs
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 configuration improves energy conversion efficiency by facilitating easier electron flow through the depletion region and reducing surface recombination, potentially achieving higher efficiencies than conventional tandem cells.
Implementation Method 1
forming a tunnel junction between the high-crystalline silicon solar cell and the high-crystalline germanium solar cell
Implementation Method 2
a first solar cell can have a bandgap energy that requires at least the absorption of a blue photon (450-495 nm wavelength) for an electron to have the bandgap energy to move from the valence band to the conduction band
Data Source
AI summary
A multi-junction solar cell comprising a high-crystalline silicon solar cell and a high-crystalline germanium solar cell. The high-crystalline silicon solar including a first p-doped layer and a n+ layer and the high-crystalline germanium solar cell including a second p layer and a heavily doped layer. The multi-junction solar cell can also be comprised of a heavily doped silicon layer on a non-light receiving back surface of the high-crystalline germanium solar cell and a tunnel junction between the high-crystalline silicon solar cell and the high-crystalline germanium solar cell.