A recent joint-research co-led by City University of Hong Kong (CityU) and Shanghai University has developed an efficient fabrication approach for all-inorganic perovskite films with better optical properties and stability, enabling the development of high color-purity and low-cost perovskite LEDs with a high operational lifetime.

The team has found that using cesium trifluoroacetate (TFA) as the cesium source in the one-step solution coating, instead of the commonly used cesium bromide (CsBr), enables fast crystallization of small-grained CsPbBr₃ perovskite crystals, forming the smooth and pinhole-free perovskite films. This is because the interaction of TFA- anions with Pb2+ cations in the CsPbX3 precursor solution greatly improves the crystallization rate of perovskite films and suppresses surface defects.

Researchers from Rutgers University, University of Minnesota and University of Texas at Dallas in the U.S have discovered a new type of electric field effect that can control light emission from perovskite devices.

The electric field effect usually refers to the modulation of electrical conductivity in a semiconductor by means of an applied voltage to a gate electrode and forms the basis of modern digital electronics. In a conventional field effect transistor (FET), the conductivity of a semiconductor layer can be turned on or off or gradually ramped up or down. Now, the research team has found that the photoluminescence (PL) of a perovskite device can be modulated in a similar manner. “Our work reports a novel type of field effect in which PL, rather than conductivity, is tuned by an ‘electric knob’ – the gate voltage,” explains Vitaly Podzorov, who led the research.