When compared to crystalline silicon-based systems, perovskites offer several advantages including, flexibility, low cost and ease of manufacture. However, only tiny cells of millimeter dimensions have been demonstrated in the laboratory. Now, Anita Ho-Baillie of the University of New South Wales reported to the Asia-Pacific Solar Research Conference in Canberra that her team has broken the conversion efficiency record for a solar cell based on perovskite materials, demonstrating a 12.1% efficiency rating for a 16 square-centimeter perovskite solar cell. This is the largest single perovskite photovoltaic cell certified with the highest energy conversion efficiency. The device is more than ten times bigger than current certified perovskite cells.
"This is a very hot area of research, with many teams competing to advance photovoltaic design," Ho-Baillie says."Perovskites came out of nowhere in 2009, with an efficiency rating of 3.8%, and have since grown in leaps and bounds." In perovskite solar cells, a hybrid organic-inorganic lead or tin halide-based material acts as the light-harvesting active layer. The inexpensive materials can even be sprayed on to a substrate. "The versatility of solution deposition of perovskite makes it possible to spray-coat, print or paint on solar cells," explains Ho-Baillie. "The diversity of chemical compositions also allows cells be transparent, or made with different colors."
Despite their early promise, perovskites have so far been of limited viability because they prone to damage from fluctuating temperatures and moisture, so that they last only a few months without sophisticated protection. Ho-Baillie's team is trying to extend the durability of these materials and based on four decades of experience with layered silicon, there is hope yet. However, low-cost, short-life solar panels might also have applications, for instance in disaster response and in charging and lighting electricity-poor regions of the world without the great expense of crystalline silicon and in situations where longevity does not matter in temporary structures for instance.
"We will capitalize on the advantages of perovskites and continue to tackle issues important for commercialization, like scaling to larger areas and improving cell durability," adds Martin Green, Ho-Baillie's supervisor. The project's goal is to lift perovskite solar cell efficiency and to eliminate lead in the perovskite solar cells.
The trick to boosting efficiency still further might lie in part to improving thin film growth so that the resulting perovskite crystals can absorb a maximum amount of light energy. There are numerous teams around the world working on this problem; it is perhaps only a matter of time where perovskites outshine silicon.
David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".