Application of $NaYF4:Yb$⁠, Er upconversion fluorescence nanocrystals for solution-processed near infrared photodetectors

In an attempt to overcome the technical challenges in the conventional solution-processed near infrared (NIR) photodetectors, we have used $NaYF4:Yb$⁠, Er upconversion fluorescence nanocrystals to replace the semiconductor quantum dots in conjugated polymers. Under NIR excitation, the $NaYF4:Yb$⁠, Er nanocrystals emit visible light in the solution-processed NIR photodetectors. The emitted visible light is simultaneously absorbed by the host conjugated polymer to generate photocurrent, which indicates that our approach is applicable to fabricate NIR photodetectors while avoiding the major technical challenges associated with semiconductor quantum dot based NIR photodetectors.