The material used to develop perovskite solar cells is based on single thin-film crystals. The way that the crystals are produced affects their efficiency. As means of creating more effective crystals, a research team have discovered that imploding bubbles in a solution can grow single crystals of the preferred orientation for manufacturing the thinnest films required for energy optimization.
Hybrid organic/inorganic perovskite materials are seemingly the promising solar cell materials for next generation device. This is because they are simple to produce and show good solar light conversion efficiencies. A perovskite is any material with the same type of crystal structure as calcium titanium oxide. With solar cells, perovskite materials such as methylammonium lead halides are the most efficient.
Current production methods of producing perovskite films are limited because the boundary between crystalline grains leads to losses. To overcome this a new bubble approach has been developed.
This new approach fabricates single-crystalline perovskite thin films by applying ultrasonic pulses to the crystal growth solution. These pulses induce tiny bubbles. The bubbles implode after a short period of time, which releases energy into the surrounding solution. When a bubble is positioned to the substrate surface, the energy released from the implosion creates jets that induce the ‘nucleation’ of perovskite crystals on the surface. This ensures a uniform distribution of the crystals and a more efficient transport of electrical charge across the device.
In trials the conversion efficiencies achieved were close to 6.5 percent — which may sound low although this is a very efficient level of solar power.
The research has been conducted at the King Abdullah University of Science and Technology (KAUST). Discussing the new process, Professor Osman Bakr states in a research note: “Our monocrystalline films provide a platform to directly implement perovskite single crystals and to elucidate their promises and challenges for solar cells.”
The research has been published in the journal Advanced Materials. The paper is titled “Solution-grown monocrystalline hybrid perovskite films for hole-transporter-free solar cells.”
