Nanostructure Sidewall Contact for Conductive Transparent Optoelectronics
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Solution Overview
Problem
Optoelectronic devices face challenges in achieving optimal electrical conductivity and optical transparency in their top contacts, particularly when operating over a wide range of wavelengths, leading to inefficiencies in solar cells and limited color control in LEDs and imaging devices.
Innovation Solution
The development of optoelectronic devices with nanostructures that feature top sidewall electrical contacts made from highly conductive materials, allowing light to enter or exit without passing through the contact, and the use of bi-layer electrical interconnects to replace tunnel junctions, enabling independent control of photo-active regions and improved current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the top electrical contact is made from optically transparent materials like ITO, then optical transparency is improved, but electrical conductivity deteriorates
Solution Approach 1:
The electrical contact is moved from a planar top contact to a three-dimensional sidewall contact structure. The contact wraps around the sidewalls of the nanostructures, allowing light to pass through the top surface without encountering the conductive material, while still providing effective electrical contact through the sidewalls.
Solution Approach 2:
The electrical contact function is extracted from the top surface and relocated to the sidewalls. This separates the optical function (top surface transparency) from the electrical function (sidewall conductivity), allowing each to be optimized independently.
2Reliability
If the top electrical contact is made from electrically conductive materials, then electrical conductivity is improved, but optical transparency deteriorates
Solution Approach 1:
The contact structure transitions from a two-dimensional top contact to a three-dimensional sidewall contact, positioning the conductive material in a location that does not obstruct the optical path while maintaining electrical functionality.
Solution Approach 2:
The conductive material is extracted from the optical path and relocated to the sidewalls, eliminating the trade-off between conductivity and transparency by spatially separating these functions.
3Illumination intensity
If optically transparent materials are used for top contacts, then optical transparency over narrow wavelength range is improved, but adaptability to wide wavelength range deteriorates
Solution Approach 1:
The electrical contact is extracted from the top surface where it would limit the wavelength range, and relocated to the sidewalls. This allows the top surface to be fully optimized for optical transparency across the entire solar spectrum without compromise from conductive material absorption characteristics.
Solution Approach 2:
By moving the contact to three-dimensional sidewalls, the patent enables the top surface to handle broad-spectrum light transmission while the sidewall contact provides wavelength-independent electrical conduction.
4Reliability
If tunnel junctions are used to allow charge carriers to flow through photoactive regions, then current flow is improved, but device complexity deteriorates
Solution Approach 1:
The electrical contact structure is merged with the nanostructure sidewalls, creating an integrated contact solution that provides both mechanical support and electrical conduction pathways without requiring separate tunnel junction components.
Solution Approach 2:
The complex tunnel junction structure is extracted and replaced with a simpler sidewall contact architecture that achieves the same current flow function through direct electrical contact with the nanostructure sidewalls.
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 solution enhances the electrical conductivity while maintaining optical transparency, allowing for efficient operation over a wide range of wavelengths and precise control of color generation or detection in optoelectronic devices, such as solar cells, LEDs, and imaging devices.
Implementation Method 1
allowing light to enter or exit without passing through the contact
Implementation Method 2
The bi-layer electrical interconnect is in electrical and physical contact with the nanostructure sidewalls
Implementation Method 3
Charge carriers are generated due to absorption of photons in the photoactive region
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Nanostructure array optoelectronic devices are disclosed. The optoelectronic device may have a top electrical contact that is physically and electrically connected to sidewalls of the array of nanostructures (e.g., nanocolumns). The top electrical contact may be located such that light can enter or leave the nanostructures without passing through the top electrical contact. Therefore, the top electrical contact can be opaque to light having wavelengths that are absorbed or generated by active regions in the nanostructures. The top electrical contact can be made from a material that is highly conductive, as no tradeoff needs to be made between optical transparency and electrical conductivity. The device could be a solar cell, LED, photo-detector, etc.