PEROVSKITE SEMICONDUCTOR OPTOELECTRONIC DEVICES

Nat. Photonics, 2019, doi: 10.1038/s41566-019-0390-x

Solution-processed metal halide perovskites (MHPs) have received significant interest for cost-effective, high-performance optoelectronic devices. In addition to the great successes in photovoltaics, their excellent luminescence and charge transport properties also make them promising for light emitting diodes (LEDs). To achieve high-efficiency perovskite LEDs (PeLEDs), extensive efforts have been carried out to enhance radiative recombination rates by confining the electrons and holes. In addition to enhancing radiative recombination rates, it is equally important to decrease the non-radiative recombination for improving the device performance. Passivation of the defects could be an efficient way for reducing the non-radiative recombination.

Recently, Feng Gao, Wei Huang, Limin Liu and their colleagues found that the candidate amino-functionalized passivation agent which form stronger hydrogen bonds with organic cations in perovskites are less effective in healing defect sites. Based on their findings, they designed new passivation molecules with decreased hydrogen-bonding ability, and hence improve their interaction with defects. In particular, they exploited O atoms within the passivation agent to polarize the passivating amino groups through the inductive effect, reducing their electron donating ability and hence relevant hydrogen-bonding ability. This results in enhanced coordination of the PA functional groups with the perovskite defect sites and hence much improved passivation efficiency. As a result, the trap mediated non-radiative recombination has been substantially decreased and a record value of 21.6% external quantum efficiency of PeLEDs has been obtained. The reports has showed us a guideline for designing molecular for surface passivation, which could be helpful for any type of perovskite optoelectronic devices.

Jingbi You (Institute of Semiconductors, CAS, Beijing, China)

doi: 10.1088/1674-4926/40/4/040203