Realizing a SnO2-based ultraviolet light-emitting diode via breaking the dipole-forbidden rule

Yongfeng Li, Wanjian Yin, Rui Deng, Rui Chen, Jing Chen, Qingyu Yan, Bin Yao, Handong Sun, Su Huai Wei*, Tom Wu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

141 Scopus citations


Although many oxide semiconductors possess wide bandgaps in the ultraviolet (UV) regime, currently the majority of them cannot efficiently emit UV light because the band-edge optical transition is forbidden in a perfect lattice as a result of the symmetry of the band-edge states. This quantum mechanical rule severely constrains the optical applications of wide-bandgap oxides, which is also the reason why so few oxides enjoy the success of ZnO. Here, using SnO 2 as an example, we demonstrate both theoretically and experimentally that UV photoluminescence and electroluminescence can be recovered and enhanced in wide-bandgap oxide thin films with 'forbidden' energy gaps by engineering their nanocrystalline structures. In our experiments, the tailored low-temperature annealing process results in a hybrid structure containing SnO2 nanocrystals in an amorphous matrix, and UV emission is observed in such hybrid SnO2 thin films, indicating that the quantum mechanical dipole-forbidden rule has been effectively overcome. Using this approach, we demonstrate the first prototypical electrically pumped UV-lightemitting diode based on nanostructured SnO2 thin films.

Original languageEnglish (US)
Article numbere30
JournalNPG Asia Materials
Issue number11
StatePublished - Nov 2012
Externally publishedYes

Bibliographical note

Funding Information:
We acknowledge support from the National Research Foundation of Singapore. The work at NREL was funded by the US Department of Energy under the Grant No. DE-AC36-08GO28308.


  • Dipole-forbidden rule
  • Electroluminescence
  • First-principles calculations
  • Light-emitting diode
  • Photoluminescence
  • Tin dioxide

ASJC Scopus subject areas

  • Modeling and Simulation
  • General Materials Science
  • Condensed Matter Physics


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