Perovskite-Silicon Tandem Solar Cell with Upconversion Layer
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Solution Overview
Problem
Current solar conversion devices, particularly perovskite-silicon tandem cells, face limitations in conversion efficiency due to the inability to absorb photons with energy lower than the bandgap of the materials used, leading to wasted solar radiation and suboptimal energy conversion.
Innovation Solution
Incorporating a metal oxide layer doped with Ho3+, Tm3+, and/or Er3+ ions, such as ZrO2, between the back contact and the passivating layer in tandem perovskite-silicon photovoltaic cells to enhance light absorption and conversion efficiency by utilizing up-conversion phenomena.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional single-junction silicon solar cells are used, then the device is simple and cost-effective, but the conversion efficiency is limited to 33% due to the bandgap limitation
Solution Approach 1:
The solar cell is divided into two separate photoelectric conversion units: a top unit with a wider bandgap material and a bottom unit with a narrower bandgap material (silicon). This segmentation allows each unit to absorb different portions of the solar spectrum, with the top unit capturing high-energy photons and the bottom unit capturing lower-energy photons, thereby overcoming the bandgap limitation and achieving higher overall conversion efficiency.
Solution Approach 2:
The patent employs composite material structures in both photoelectric conversion units. The top unit uses perovskite materials with tailored compositions (e.g., mixed halide perovskites) to achieve desired bandgap values, while the bottom unit uses silicon-based materials. These composite material systems enable optimized light absorption across different spectral regions while maintaining structural integrity and electrical functionality.
2Productivity
If perovskite-silicon tandem structure is implemented, then the theoretical efficiency limit increases to 43%, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
An intermediate layer is introduced between the top perovskite photoelectric conversion unit and the bottom silicon photoelectric conversion unit. This intermediate layer serves multiple functions: it acts as a selective contact to facilitate charge carrier extraction, provides optical management to minimize parasitic absorption, and ensures good electrical contact between the two units. The intermediate layer simplifies the manufacturing process by enabling modular assembly and reducing the complexity of interface engineering.
Solution Approach 2:
The patent optimizes various parameters including the bandgap values of the perovskite materials, the thickness of each layer, the doping concentrations in the intermediate layer, and the optical properties of the structure. By carefully tuning these parameters, the device achieves optimal current matching between the top and bottom units, maximizing overall efficiency while maintaining manufacturability through standardized material systems.
3Productivity
If up-conversion materials are added to absorb low energy photons, then the utilization of solar spectrum is enhanced, but the device complexity and parasitic absorption losses increase
Solution Approach 1:
The patent incorporates up-conversion materials that convert low-energy photons (which would otherwise be lost) into higher-energy photons that can be absorbed by the silicon bottom cell. This transforms the harmful effect of parasitic absorption in the silicon (which cannot absorb photons below its bandgap) into a beneficial up-conversion process, extending the usable solar spectrum and increasing overall energy utilization without significant additional complexity.
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 increases the electrical conversion efficiency of solar cells beyond the theoretical limits, allowing for the effective utilization of a wider range of solar spectrum, potentially achieving conversion efficiencies over 30%, while reducing parasitic absorption losses and enhancing stability and cost-effectiveness.
Implementation Method 1
Photon up-conversion is a process in which the sequential absorption of two or more low energy photons leads to the emission of single-photon with higher energy. Upconverters absorb high wavelength photons, i.e., greater than 1100 nm, and convert these high wavelength photons to a lower wavelength, i.e., less than 1100 nm
Implementation Method 2
Solar cells are used to convert solar energy into electrical energy
Data Source
AI summary
A perovskite-silicon tandem cell capable of absorbing solar radiation with energy lower than that of 1.12 eV, i.e., the bandgap of crystalline silicon—corresponding to the wavelength of 1100 nm. Ho3+ can absorb photons of wavelength range 1120 to 1190 nm, Tm3+, 1190 to 1260 nm, and Er3+, 1145 to 1580 nm, but up-conversion can be achieved using Ho3+, Tm3+, and Er3+-doped metal oxide, such as ZrO2, in perovskite-silicon tandem solar cells. Doped metal oxides, such as ZrO2 can also work as selective contacts. Such perovskite-silicon tandem structures can achieve over 30% solar energy conversion efficiency.