![]() ![]() The award citation said John and his team had “recently applied their light-trapping ideas into the design of flexible, lightweight, thin-film silicon solar cells that can be coated on a variety of surfaces, with unprecedented sunlight capture capabilities and power-conversion efficiencies well beyond that of standard solar panels”. The invention and development of photonic crystals won John Canada’s highest science and engineering prize, the prestigious Gerhard Herzberg Canada Gold Medal, this month. One utility of the invention is that thin silicon solar cells can be encapsulated in flexible sheets to generate power on surfaces like walls, or even in clothing like a winter coat that can provide a charging facility for devices like cellphones. Photonic crystals are also known as the “semiconductors of light” because they control photons much like electronic semiconductors control electrons. He said the photonic crystal architecture allows for cells that are 50% more efficient than those currently in use. “When we can do that and absorb most of the sunlight or more than what they were getting with thick silicon, it means that the photo-generated charge carriers can reach their contacts before they get distracted and de-activated by something else.” John’s photonic crystal design is aimed at minimising that wastage with a much thinner structure, only 10 microns thick. The problem is that in such thick solar cells, electrons excited by the sunlight need to travel a long distance to metallic contacts and before that, energy dissipates in the form of heat and some of the sunlight doesn’t get converted to electricity. In traditional approaches, silicon is made very thick, at 300 microns, thrice the thickness of a human hair, so as to enhance the absorption of sunlight. While efficient at absorbing shortwave light, they perform poorly with red or near infrared light. Traditional silicon cells are not ideal at absorbing a broad range of sunlight. As a result, the light can be absorbed almost completely in a flexible film of silicon only one-tenth the thickness of a human hair, for highly efficient electrical power generation. Certain photonic crystal architectures can be very effective in capturing sunlight and making it bounce around for a prolonged time in a thin material. In an interview with the Hindustan Times, Prof John, who was born in Thiruvalla in Kerala, said his design is based on “the invention of photonic crystals”, the novel materials that can trap and guide light on a microscopic scale. Production company or studio.Applications based on the research conducted by University of Toronto professor of physics Sajeev John are currently in progress. Here is the basic format for a reference list entry of a documentary in APA style 7th edition:ĭirector(s) of the documentary. More description information can be included - for example 'Film DVD' or 'Film extended edition DVD'
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