Missions

The missions will be divided into three stages:
1. Theoretical evaluation of TPV cell architectures for high-temperature thermal radiation conversion:
Implementation of a theoretical model (extended detailed balance) to specify the optimum choices in terms of cell bandgap, and spectral selectivity achieved by a photonic component, taking into account the thermal equilibrium of the cell with its environment. This approach will notably lead to the specification of the photonic component providing spectral selectivity and the cell's operating temperature (or the heat to be dissipated to maintain the cell at a temperature close to 25°C).
2. Optical and electrical modeling for the design of a III-V semiconductor-based TPV cell architecture:
Implementation of optical models to define a photonic structure providing the spectral filtering defined in step 1. Implementation of an optoelectronic simulator to define the photovoltaic cell architecture under illumination from a high-temperature thermal emitter, maximizing performance (compromise between electrical power and efficiency). At this stage, the choice will be made for a cell based on III-As(N) semiconductors with an adjustable bandgap in the target range 0.8 - 1.1 eV.
3. Experimental realization of TPV cell demonstrators:
Fabrication and characterization of the spectral filter and TPV cell designed in stage 2. Fabrication will be carried out using cleanroom micro-nano fabrication processes (molecular beam epitaxy, etching, deposition, etc.). Performance characterization will initially be carried out in the laboratory (LAAS-CNRS), and ultimately in real operating conditions using a high-temperature emitter under concentrated solar illumination (PROMES).

The work will be carried out at LAAS in close collaboration with the PROMES laboratory.

Activities

Literature review of photonic structures capable of achieving spectral selectivity.
Implementation of a theoretical model based on the detailed balance approach.
Use of photonic and optoelectronic simulation codes to design the cell structure.
Implementation of clean-room processes.
Characterization of cell performance and material properties.

Skills

Skills in physics, optics, materials science and semiconductor physics, physics of photovoltaic conversion.
Strong motivation for experimental work, preferably with experience in clean-room processes.
General skills: organization, problem-solving, communication, teamwork.

Work Context

Among the many storage solutions currently being studied to enhance the dispatchability of renewable energies and promote a better match between production and demand, thermophotovoltaic (TPV) high-temperature heat conversion is undeniably one of the most promising options, both technologically and economically. This technology for the thermal storage of concentrated solar energy or even electrical energy (known as "power-to-heat"), followed by conversion into electricity, is based on the combination of two key components: 1) a thermal radiation emitter heated to very high temperatures; 2) a thermophotovoltaic conversion module, enabling the radiation emitted by the hot body to be converted into electricity. While this concept of storing energy in thermal form at high temperatures has been the subject of several theoretical assessments in recent years, the experimental demonstration of its efficient conversion has been the subject of a recent high-profile publication: a conversion efficiency of 40% has been measured on tandem cell architectures exposed to radiation emitted by a heat source with a temperature of between 2000 and 2400°C.
In this context, the project aims to develop a TPV cell technology optimized for the conversion of energy stored at very high temperatures, in the range from 1500 to 2000°C. This temperature range has been little covered to date. It requires photovoltaic cells with bandgap energies between 0.8 eV (InGaAs alloy) and 1.1 eV (silicon).
A number of scientific and technological challenges will have to be tackled, since TPV cells will have to ensure:
- optimal spectral selectivity,
- high performance (efficiency, power),
- minimal resistive losses.

The post-doctorate is funded by the PV-STAR key challenge (https://pvstar.cnrs.fr/) of the Occitanie Region.

The position is located in a sector under the protection of scientific and technical potential (PPST), and therefore requires, in accordance with the regulations, that your arrival is authorized by the competent authority of the MESR.

Constraints and risks

Preliminary training for the use of clean-room processes.