Highly Sensitive UV Photodiode Composed of beta-Polyfluorene/YZnO Nanorod Organic-Inorganic Hybrid Heterostructure

Abstract

The highly sensitive ultra-violet (UV) photodiode was demonstrated on the organic-inorganic hybrid heterostructure of beta-phase p-type polyfluorene (PFO)/n-type yttrium-doped zinc oxide nanorods (YZO-NRs). The device was fabricated through a simple fabrication technique of beta-phase PFO coating onto YZO-NRs that had been directly grown on graphene by the hydrothermal synthesis method. Under UV illumination (lambda = 365 nm), the device clearly showed excellent photoresponse characteristics (e.g., high quantum efficiency similar to 690%, high photodetectivity similar to 3.34 x 10(12)cm.Hz(1/2).W-1, and fast response time similar to 0.17 s). Furthermore, the ratio of the photo current-to-dark current exceeds 10(3)even under UV illumination with a small optical power density of 0.6 mW/cm(2). We attribute such superb photoresponse characteristics to both Y incorporation into YZO-NRs and conformation of beta-phase PFO. Namely, Y dopants could effectively reduce surface states at YZO-NRs, and beta-phase PFO might increase the photocarrier conductivity in PFO. The results suggest that the beta-phase p-PFO/n-YZO-NR hybrid heterostructure holds promise for high-performance UV photodetectors.