This article is part of an ongoing State of Innovation series exploring global inventions and innovation trends in 12 key industries. Download the State of Innovation report on the Semiconductor industry now, or download the full 2017 report here.
Earlier this year, for the first time in 135 years since the Industrial Revolution, the UK went for 24 hours without a single piece of coal being burned in a power station to provide the nation’s energy needs. Those needs were met entirely by a mixture of gas, nuclear and renewable sources.
Dwindling reserves of fossil fuels have sparked a wave of innovation in energy, and with the world’s energy consumption set to increase 35 percent by 2035, the need to develop renewable and cleaner alternatives is paramount. Among a mix of wind, water, biomass and nuclear, solar power has a significant role to play, especially in developing areas with high levels of sunlight.
Step forward a revolutionary new development: solar paint. Also known as paint-on/spray-on solar or paintable solar, this is a radical new alternative to the expensive, large, bulky, brittle, rigid silicon flat panels we see on rooftops today. The emerging breakthrough technology offers a low-cost way to harness the sun’s energy with a much wider range of applications. The idea is that you can solar-paint on to various surfaces regardless of shape, e.g., sides of buildings, roofs, vehicles and just about any other structure you can think of that faces the sun.
“Step forward a revolutionary new development: solar paint.”
Liquid solar paints consist of a range of materials known as perovskites that scientists believe will revolutionize solar energy, a roughly $55 billion industry. Perovskite can be mixed in liquid solutions to allow it to be deposited on a variety of surfaces. It can be mixed with a range of chemicals to produce a crystallized lattice, to form very lightweight films.
The potential of perovskite for solar cells was discovered in 2006 by Japanese researchers. But because its structure was poorly understood and because the industry had latched onto silicon for solar electricity, perovskite went largely ignored, according to Tsutomu Miyasaka, who first suggested its usefulness. The technology developed through perovskite solar cells based on organometal halides in dye-sensitized solar cells. In a liquid-based dye-sensitized solar cell structure, the adsorption of methylammonium lead halide perovskite on a nanocrystalline TiO2 surface produces a photocurrent with a power conversion efficiency (PCE) of around 3 to 4 percent, as first discovered in 2009.
The PCE was doubled after two years by optimizing the perovskite coating conditions. However, liquid-based perovskite solar cell received little attention because of stability issues. Those problems were solved in 2012, with the development of a long-term, stable and high-efficiency (up to 10 percent) perovskite solar cell, which substitutes the solid hole conductor with a liquid electrolyte. The major breakthrough prompted scientists to experiment with perovskite with increasing enthusiasm.
The first spray-on solar cells came in 2014 from the UK’s University of Sheffield, which became the first to produce new spray-on solar cells using a spray-painting process. Lead researcher Professor David Lidzey said, “The best certified efficiencies from organic solar cells are around 10 percent. Perovskite cells now have efficiencies of up to 19 percent. This is not so far behind that of silicon at 25 percent – the material that dominates the world-wide solar market.”
Improvements in PCE continue, with the highest efficiency rating of 12.1 percent conversion rate with the largest perovskite solar cells to date (16 cm2) being achieved in December 2016 by Dr. Anita Ho-Baillie and her Perovskite Solar Cell Research team at the Australian Centre for Advanced Photovoltaics at UNSW. They also achieved an 18 percent efficiency rating on a 1.2 cm2 single perovskite cell.
Today, since PCE values over 20 percent are realistically anticipated (coming close to the 25 percent efficiencies of conventional silicon solar cells) with the use of cheap organometal halide perovskite materials, perovskite solar cells hold out great promise to reduce our reliance on non-renewable energy sources and contribute to a cleaner, energy-secure world in the future.
To learn more, read the State of Innovation report on the Semiconductor industry, or download the full 2017 report here, which showcases latest inventions from around the world and focuses on trends in the top 12 industries.