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Sunlight-harvesting films reveal their secrets

Published online 26 November 2016

Balancing temperature makes for smarter light-harvesting polycrystalline films

Biplab Das

Solar cells made of perovskite materials efficiently convert sunlight to electricity, with a power-conversion efficiency of 20%.

The effect of nano or microstructures on charge transport in perovskite materials has been largely unknown.

Now, scientists from Saudi Arabia and the UK tried to dispel the mystery by studying how microstructures shape the optical and electronic properties of pure crystalline perovskite films that are made of methylammonium lead iodide1.

“This research offers a way to control crystal orientation in large-area hybrid perovskite films which could potentially be used to make solar cells, phototransistors and photodetectors,” says lead researcher Osman M. Bakr from the King Abdullah University of Science and Technology (KAUST), Saudi Arabia.  

By controlling temperature and concentration of methylammonium iodide and lead iodide in an ionic liquid, the scientists grew polycrystalline films containing branch-like microstructures. When exposed to extremely short pulses of laser and visible light, the films would show spontaneous emission and would generate a light-induced current. 

These films have low number of traps, which are usually generated due to impurities and defects in materials. Such traps can capture mobile electrons, so the fewer traps, the more coherent the light emitted by the films. 

These properties position the films as excellent material for manufacturing optoelectronic devices, the researchers say.


  1. Cho, N. et al. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films. Nat. Commun. (2016).