In order to reduce carbon emissions and mitigate the effects of climate change, the energy sector requires an urgent energy transition at a global scale. In the domain of photovoltaics, despite the great effort devoted for large scale implementation, price reduction is still the main concern to become fully cost-competitive with traditional energy sources. In this frame, two main parameters can lead to photovoltaic cost-per-Watt reduction, namely higher conversion efficiency and lower production cost.
The purpose of INMoSt is the realization of low-cost, high-efficiency, multi-junction solar cells using a single material family, namely III-nitride semiconductors. This target becomes possible by combination of a series of innovative technologies. First, recent developments of the InGaN-nanopyramid growth method have made it possible to enhance the In incorporation in the material which reducing the density of structural defects. Then, the implementation of an h-BN-based simple lift-off and transfer process allow a drastic reduction of the fabrication costs. Finally, the improvement of the conductivity of the p-region and of the p-contact is now possible by depositing Mg-doped layers by molecular-beam epitaxy and using an n+/p+ tunnel contact scheme. The combination of these recent breakthroughs have set the basis for the implementation of low-cost (re-use of the substrate) and high-efficiency InGaN solar cells. The first milestone will be the demonstration of beyond-state-of-the-art, free-standing, and flexible InGaN-based solar cells. This will be realized by the encapsulation into PDMS of the lifted-off solar cells. The ultimate goal will be the fabrication of a stack of such solar cells, each step with a different band gap in order to grant access to a large region of the solar spectrum, and using a process fully compatible with conventional integrated circuit production technology.
The INMoSt consortium brings together two partners with complementary experimental and theoretical expertise and capabilities: GT CNRS and CEA-IRIG-PHELIQS. INMoSt researchers possess backgrounds in science and engineering with expertise in experimental and theoretical aspects of nitride materials and nanostructures, growth kinetics, semiconductor fabrication processes, material characterization, and device physics. The functional strategy of the project is based on three main building blocks of technology optimization: simulation and design, epitaxial growth and device fabrication. Assessment of these building blocks will be assisted by material characterization and device tests and measurements.
Photovoltaics is becoming a major industry, with constant growth in terms of economic and social benefits. Preparing the next steps of development, in particular the 30-30-30 challenge (production of photovoltaic modules with a >30% energy conversion efficiency for a <30 c$/Wp price by 2030), starting from basic research and innovation is extremely important. INMoSt will provide the first low-cost, high-efficiency, multi-junction solar cells (SC) using a single material family, namely III-nitride semiconductors.
Monsieur Jean Paul Salvestrini (Unité Mixte Internationale GT CNRS)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
PHELIQS Photonique Electronique et Ingénierie Quantiques
UMI GT CNRS Unité Mixte Internationale GT CNRS
Help of the ANR 386,883 euros
Beginning and duration of the scientific project: January 2020 - 48 Months