Third Generation Spectral Engineering for Increased Solar Cell Efficiencies

::Download Scientific Description::   ::Project Researchers and Highly Qualified Personnel::    Third generation photovoltaic technologies seek to introduce new physical mechanisms that could, in principle, move beyond the Shockley-Queisser limit of  ˜30% energy conversion efficiency for a single junction solar cell. Significant increases in the efficiency of photovoltaic devices, preferably using low cost manufacturing methods such as thin film technologies, would be transformational in reducing the energy costs to grid parity – i.e. comparable to other utility scale sources.

Group Photo for PROJECT8

left to right: Professor Rafael Kleiman (Project Leader – McMaster University), Dan Frisina (MSc student – McMaster University), Matthew Wilkins (MSc student – University of Ottawa), Professor Karin Hinzer (Project Co-Investigator – University of Ottawa), and Ahmed Gabr (PhD student – University of Ottawa).

The central challenge in achieving higher conversion efficiencies is the broad range of wavelengths in the solar spectrum. One approach to increased device efficiency is via up- and/or down-conversion of the photon energies in the solar spectrum. In down-conversion, high energy photons are split into two or more lower energy photons, whereas in up-conversion, two or more low energy photons are combined to form a higher energy photon. This effectively narrows the spectrum illuminating the solar cell, leading to higher energy conversion efficiency.

This approach is purely optical in nature, and simplifies progress by permitting optimization of the performance of up- and down-conversion layers separately from that of the solar cell. High up- and/or down-conversion efficiency is essential for these processes to lead to a net gain in the energy conversion efficiency of the solar cell. In this project, we seek to develop new materials systems with efficient up- and down-conversion processes for incorporation into conventional solar cells and/or modules to enhance their energy conversion efficiency.

Figure: Transmission electron microscope image of silicon nano-crystals in a silicon oxide matrix. Silicon nano-crystals are one potential candidate for up/down-converting photonic coatings. [Source: Fig 4.32 from the thesis of Master’s level HQP, Justin Sacks]

Figure: A plasma-enhanced chemical vapour deposition system is used to create silicon nano-crystals at McMaster University in an attempt to develop up and down-converting optical materials. [Source: Co-Investigator Peter Mascher]