NREL’s Jerry Olson honoured with Cherry Award from IEEE
A physicist from the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) who was a pioneer in III-V multi-junction solar cells for use in outer space and on Earth has been awarded the prestigious Cherry Award by the Institute of Electrical and Electronics Engineers (IEEE).
Figure 1. NREL Principal Scientist, Jerry Olson holds one of the first multi junction cells that were developed in the 1980s from his technology. (Credit: Dennis Schroeder)
Jerry Olson, a principal scientist at NREL, received the award at the IEEE’s annual Photovoltaic Specialists Conference in Seattle.
Figure 2. NREL post-doc, John Simon, left, and NREL Principal Scientist, Jerry Olson, right, view test materials in an MBE reactor in their lab at the Solar Energy Research Facility at NREL in Golden, Colorado. (Credit: Dennis Schroeder)
Olson opened the door for multi-junction solar cells by showing that a top cell of GaInP and a bottom cell of GaAs can capture and convert photons more efficiently into electricity than previous attempts at using other materials.
He and his co-workers showed that the multi-junction concentrator cells not only use a fraction of the precious electronic materials used by the thicker flat plate cells, but that they can capture more light through the course of a day.
Figure 3. A stack of plates with wafers being prepped for coating in the MBE kit at NREL.
(Credit: Dennis Schroeder).
Olson’s 1984 breakthrough was embraced by NASA, which uses multi-junction solar cells based on his invention to power most space satellites, as well as the Mars rovers, Spirit and Opportunity.
Olson, then a rookie in multi-junction solar, reviewed some technical reports on the subject and had a brand new thought. Most groups working in the field were looking for band gap combination that would yield maximum theoretical efficiency with less emphasis on the chemical and structural compatibility of the different semiconductor layers. In essence they were “trying too hard to hit the bull’s eye,” he said.
The key was to find materials that were compatible (and more likely to be manufactured) but that still had a band gap combination that would deliver high theoretical efficiency. That combination was a top cell of GaInP with a band gap of 1.9 eV and a bottom cell of GaAs with a band gap of 1.4 eV. These two semiconductors are chemically compatible and have the same lattice constant, a measure of their structural compatibility.
Figure 4 : NREL research technician Waldo Olavarria, left, changes a quartz reactor tube in the atmospheric reactor as NREL Principal Scientist, Jerry Olson, right, watches. (Credit: Dennis Schroeder)
The Cherry Award is named in honour of William R. Cherry, a founder of the photovoltaic community. In the 1950s, he was instrumental in establishing solar cells as the ideal power source for space satellites and for recognising, advocating, and nurturing the use of photovoltaic systems for terrestrial applications.
The William R. Cherry award was instituted in 1980, shortly after his death. The purpose of the award is to recognise individual engineers or scientists who devoted a part of their professional life to the advancement of the science and technology of photovoltaic energy conversion.
It is only awarded to scientists who are still actively contributing to the field.
Figure 5. Jerry Olson holds a wafer that contains 11 diagnostic solar cells to be tested at NREL. The cells are used with a solar concentrator and are 3 µm thick. They convert more than 20 % of the photons that hit them into usable electricity. (Credit: Dennis Schroeder).
NREl says that today’s PV concentrators, which can extract 30 to 40 watts out of a small 1-square-centimetre solar cell by using lenses to focus the power of a thousand suns on the cell, are a direct descendant of Olson’s multi-junction breakthrough.
Sarah Kurtz, NREL’s acting director of the National Centre for Photovoltaics at NREL, joined the lab a couple years after Olson’s watershed invention. The pair has been instrumental in clearing hurdles to ensure that the GaInP/GaAs solar cell remains the top cell for efficiency.
“Jerry wasn’t dissuaded by things in the literature that might give erroneous directions,” Kurtz said. “The brilliance of his achievement was partly that he was willing to set that aside even in the face of people telling him that his approach would never work."
