Nano and Micro-Structured Devices for Cleaner Energy

We aim to control photons, phonons, and electrons in new devices for a sustainable world. This can be achieved by patterning materials at small dimensions, obtaining better efficiencies and overcoming challenges of existing technologies like solar cells.

In this project we will generate algorithms of optimization to develop generic solution paths for applications of structured materials to solve day-to-day problems, starting with highly improving the efficiency of solar cells.

The process of materials absorbing light energy to further convert it into electrons current is yet to be optimized in many technologies, including in solar cell devices. Thermal emission control, or the reciprocal phenomenon, absorption of electromagnetic radiation, is crucial in heat management, energy harvesting and conversion, or producing novel sources and detectors. The development of micro and nano-structured materials has led to remarkable effects in heat-light conversion and transfer, due to photon-electrons or phonon-electrons interactions at the subwavelength scales of light. Photons are the quanta for electromagnetic radiation, and vibrational energy in solids has the quanta of phonons. These quasiparticles play a major role in thermal conductivity and energy conversion. The energy is transferred through the solid with the vibrational energy of the lattice.

The directionality of the radiation to increase absorption in solar cells can be achieved with structured metals or glass coated on Si cells via plasmonic and phononic effects. In addition, via radiative cooler, we can generate light from darkness with thermoelectric generators where the cold side radiates heat to the cold of space by facing the night sky, by coating the Si surface. Efficient radiative coolers for solar energy applications must be transparent in the visible and near-infrared spectrum and highly emissive in the thermal wavelengths (> 4μm), promising materials are glasses or emissive polymers. Since the energy radiated is directly proportional to the material’s emissivity, which depends strongly on the geometry and the surface. Nano or micro-holes can be fabricated to achieve effects like extraordinary transmission to increase the absorption from the VIS to the midIR spectrum. Also, gratings and more complex geometry configurations can be achieved in a scalable way due to new fabrication techniques.

Applying a hybrid photonic and phononic patterning results in a surface-structuring on the micro or nanoscale. We can manipulate these properties to make solar selective materials to operate from the visible to the mid-infrared electromagnetic region. We will develop algorithms of optimization for nano and micro patterns of coated films, characterizing the devices with spectroscopy in all these wavelength regions, as well as optimizing solar cell fabrication and device operation. Working together for 48 hrs and brainstorming in a team with diverse skills and capabilities, we will propose a hybrid structured device that combines the effective use of photons and phonons for solar cell optimization.

Group Leader

R. Margoth Córdova-Castro, Lindau Alumna 2019
University of Ottawa, Canada