Low Dark-Current, High Current-Gain of PVK/ZnO Nanoparticles Composite-Based UV Photodetector by PN-Heterojunction Control

• Published in: Sensors (Basel, Switzerland) Vol. 16; no. 1; p. 74
• Main Authors: Lee, Sang-Won, Cha, Seung-Hwan, Choi, Kyung-Jae, Kang, Byoung-Ho, Lee, Jae-Sung, Kim, Sae-Wan, Kim, Ju-Seong, Jeong, Hyun-Min, Gopalan, Sai-Anand, Kwon, Dae-Hyuk, Kang, Shin-Won
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 07.01.2016; MDPI
• Subjects: Composite materials; Doping; Engineering; Glass substrates; hybrid photoactive layer; Metal Nanoparticles - chemistry; Metal oxides; Nanocomposites - chemistry; Nanoparticles; Optical properties; Photochemical Processes; Photocurrent; Photodetectors; Photoelectric effect; pn-heterojunction; Polymers; Polyvinyl carbazole; Polyvinyls - chemistry; Sensors; Spectrophotometry, Ultraviolet; UV photodetector; Zinc oxide; Zinc Oxide - chemistry; ZnO nanoparticles; hybrid photoactive layer; UV photodetector; ZnO nanoparticles; pn-heterojunction
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s16010074

We propose a solution-processable ultraviolet (UV) photodetector with a pn-heterojunction hybrid photoactive layer (HPL) that is composed of poly-n-vinylcarbazole (PVK) as a p-type polymer and ZnO nanoparticles (NPs) as an n-type metal oxide. To observe the effective photo-inducing ability of the UV photodetector, we analyzed the optical and electrical properties of HPL which is controlled by the doping concentration of n-type ZnO NPs in PVK matrix. Additionally, we confirmed that the optical properties of HPL dominantly depend on the ZnO NPs from the UV-vis absorption and the photoluminescence (PL) spectral measurements. This HPL can induce efficient charge transfer in the localized narrow pn-heterojunction domain and increases the photocurrent gain. It is essential that proper doping concentration of n-type ZnO NPs in polymer matrix is obtained to improve the performance of the UV photodetector. When the ZnO NPs are doped with the optimized concentration of 3.4 wt.%, the electrical properties of the photocurrent are significantly increased. The ratio of the photocurrent was approximately 10³ higher than that of the dark current.