Researchers have developed a method of building the next generation of perovskite solar cells to make an efficient source of renewable energy.
Researchers from Nanyang Technological University, Singapore, have collaborated with the University of Groningen, Netherlands, to develop a method to develop a method of analysing which pairs of materials in next-generation perovskite solar cells will harvest the most energy.
Published in Science Advances, Physicists Professor Sum Tze Chien from Nanyang Technological University and Professor Maxim Pshenichnikov from University of Groningen used extremely fast lasers to observe how an energy barrier forms when perovskite is joined with a material that extracts the electrical charges to make solar cells.
Conventionally, solar cells absorb sunlight and convert it into electrical charge. During this process, the light particles have more energy than needed to generate the electrical charges in the solar cells.
The excess energy gives rise to what are called ‘hot’ charges, which lose their excess heat energy very fast, leaving only ‘cold’ charges available for electrical power generation.
This energy loss is why conventional solar cells have a theoretical limit of 33% for power conversion efficiency. The best perovskite solar cells so far have exhibited 25% efficiency, which is almost on par with the best performing silicon solar cells.
The key to extracting these hot charges quickly lies in the selection of the correct extraction material to bond with the perovskite. Professor Sum’s team have now devised a method of measuring which are the best extraction materials.
Professor Sum, the Associate Chair (Research) at NTU’s School of Physical and Mathematical Sciences, said “Our latest findings show how ‘hot’ these charges have to be, in order to cross over the energy barrier without being wasted as heat. This highlights the need for better pairing of ‘extraction’ materials with perovskites if we want to lower this energy barrier for more efficient solar cells.”
The primary advantage of perovskite solar cells over silicon solar cells is that they are cheap and easy to manufacture using common chemistry laboratory supplies and do not need silicon’s costly energy intensive manufacturing processes.