Notably Improved Red Photoresponse of Organic Diode Employing Gold Nanoparticles Plasmonic Absorption.

The wide variation of optical absorptions of AuNPs provides a strategy to fabricate simple photosensitive sensors. We demonstrate a notably improved red photoresponse of organic diode by incorporation of 3-nm gold nanoparticles (AuNPs) into NPB/C-60 heterojunction interface. Near-field enhancement around AuNPs gives rise to the significant improvement of exciton generation and dissociation in the interface of organic photodiode (OPD), thereby obtaining a sharply increasing photocurrent. A detailed energy level diagram is proposed to interpret the improvement of photocurrent. Significantly, the OPD exhibits excellent diode characteristics in the dark. On the other hand, the device shows a large red photoresponse with responsivity greater than 200 mA/W. The calculated maximum D* and EQE are 1.52 x 10(11) jones and 39.21% at a very low voltage of -0.5 V, respectively. Note that the NPB and C-60 almost have no absorption at 650 nm; the red photoresponse performance above is one of the highest values reported thus far for the single AuNPs layer dominant OPDs. It is expected that such a red-light detector will have potential application in future optoelectronic devices.