I have fabricated a colloidal quantum dot LED from CdSe/ZnS nanocrystals. The luminous intensity degraded with number of trials. The resistance of the device also reduced from few MOhm to few kOhms. Is there a way to overcome this problem?
Have you saw any red shift of EL spectrum or carrier lifetime change? It might be ion diffusion during measurement.
I did not see a red shift. The EL is same as the PL.
What are these ions, metal?
Is there a way to overcome this problem?
The emission might come from band edge emission or defect related emission. The Cd/Zn inter-diffusion might occur at high temperature. Have you check the junction temperature or IV curve with each trial? To reduce this degradation, you can try to measure EL with lower current level, pulse current source, or better heat sink for reducing joule heat. Hope it can work for your device.
Thank you for the reply.
I think its the heating effect at high current.
- Badges
- Science topic