Published on February 2nd, 2015 | by James Ayre1
Single Crystal Perovskites — Emerging Family Of Solar-Absorbing Materials Paves Way Towards More-Efficient & Potentially Cheaper Solar Cells
February 2nd, 2015 by James Ayre
While perovskites have been a mainstay of solar energy research for some time now, the purest form of the material — perfect single crystals of perovskite — had never been investigated very deeply.
That’s changed now, though, with the release of new research findings from the University of Toronto + the King Abdullah University of Science and Technology.
The new research utilized a “new technique” to grow rather large, pure crystals of perovskite — and then studied the way that electrons move through the material as electricity is created from the light.
“Our work identifies the bar for the ultimate solar energy-harvesting potential of perovskites,” stated Riccardo Comin, a post-doctoral fellow with the Sargent Group. “With these materials it’s been a race to try to get record efficiencies, and our results indicate that progress is slated to continue without slowing down.”
Here’s an explanation of the work via a recent press release:
The team used a combination of laser-based techniques to measure selected properties of the perovskite crystals. By tracking down the rapid motion of electrons in the material, they have been able to determine the diffusion length — how far electrons can travel without getting trapped by imperfections in the material — as well as mobility — how fast the electrons can move through the material.
In recent years, perovskite efficiency has soared to certified efficiencies of just over 20%, beginning to approach the present-day performance of commercial-grade silicon-based solar panels mounted in Spanish deserts and on Californian roofs.
“In their efficiency, perovskites are closely approaching conventional materials that have already been commercialized,” explained Valerio Adinolfi, a PhD candidate in the Sargent Group and co-first author on the paper. “They have the potential to offer further progress on reducing the cost of solar electricity in light of their convenient manufacturability from a liquid chemical precursor.”
Beyond solar energy applications, the new research has potential implications for the field of lighting solutions. The applications in lighting would be essentially just the opposite of this one in solar energy — send electrons through a slab of perovskite crystals, and enjoy the light released, rather than the other way around. This application will depend upon it being demonstrated as being economical of course, something that certainly isn’t a guarantee.
Associated/complementary work being done through the Sargent Group is focusing on colloidal quantum dots.
“Perovskites are great visible-light harvesters, and quantum dots are great for infrared,” stated lead researcher Professor Ted Sargent, of The Edward S Rogers Sr Department of Electrical & Computer Engineering at the University of Toronto. “The materials are highly complementary in solar energy harvesting in view of the sun’s broad visible and infrared power spectrum.”
“In future, we will explore the opportunities for stacking together complementary absorbent materials,” chimed in Dr Comin. “There are very promising prospects for combining perovskite work and quantum dot work for further boosting the efficiency.”
The new findings were recently published in the journal Science.