Multilayered Nanostructure Solar Cell with Cascaded Ionization
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Solution Overview
Problem
Conventional single-junction silicon solar cells are limited by the Shockley-Queisser limit, achieving a maximum efficiency of 29% due to energy loss to heat from photons exceeding the bandgap energy, and existing techniques like multi-exciton generation and secondary excitation have not been effective in surpassing this limit.
Innovation Solution
The development of optical-to-electrical energy conversion devices utilizing multilayered nanostructures with a core-shell structure and heavily compensated p-n junctions, employing a cascaded exciton ionization mechanism to generate multiple electron-hole pairs from a single photon, thereby increasing conversion efficiency beyond the Shockley-Queisser limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional single-junction silicon solar cells are used, then the device structure is simple and easy to manufacture, but the energy conversion efficiency is limited to maximum 29% due to the Shockley-Queisser limit
Solution Approach 1:
The solar cell structure is segmented into multiple functional regions including a p-type substrate, n-type emitter layer, and heavily compensated base region. This segmentation allows each region to perform specific functions optimized for high efficiency while maintaining manufacturability through standard semiconductor processing techniques.
Solution Approach 2:
The patent changes the doping parameters by introducing a heavily compensated base region with specific donor and acceptor dopant concentrations. This parameter change enables the base region to exhibit unique electrical properties that enhance carrier collection efficiency and overcome the Shockley-Queisser limit while using conventional silicon materials and processes.
2Productivity
If multi-exciton generation and secondary excitation techniques are employed to surpass the Shockley-Queisser limit, then energy conversion efficiency may improve, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of complex multi-junction structures or exotic materials, the patent achieves enhanced efficiency by changing the doping parameters in a single-junction silicon cell. The heavily compensated base region with controlled dopant concentrations creates favorable carrier transport conditions that enable efficiencies above 29% using simple, well-understood physics and conventional manufacturing.
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 achieves energy conversion efficiencies greater than 48% in single-junction Si solar cells, nearly doubling the theoretical limit, with the cascaded exciton ionization mechanism allowing for efficient energy conversion at low or zero bias, reducing energy loss and enhancing photocurrent.
Implementation Method 1
The multilayered nanostructures of the optical-to-electrical energy conversion device are structured to provide an optical active region capable of absorbing photons from light at one or more wavelengths to generate an electrical signal
Implementation Method 2
employing a cascaded exciton ionization mechanism to generate multiple electron-hole pairs from a single photon, thereby increasing conversion efficiency beyond the Shockley-Queisser limit
Data Source
AI summary
Methods, systems, and devices are disclosed for implementing high conversion efficiency solar cells. In one aspect, an optical-to-electrical energy conversion device includes a substrate formed of a doped semiconductor material and having a first region and a second region, an array of multilayered nanoscale structures protruding from the first region of the substrate, in which the nanoscale structures are formed of a first co-doped semiconductor material covered by a layer of a second co-doped semiconductor material forming a core-shell structure, the layer covering at least a portion of the doped semiconductor material of the substrate in the second region, and an electrode formed on the layer-covered portion of the substrate in the second region, in which the multilayered nanoscale structures provide an optical active region capable of absorbing photons from light at one or more wavelengths to generate an electrical signal presented at the electrode.