Effect of Metallic Nanoparticles on the Photodetection Behavior of an Organic Phototransistor

• Main Authors: Shuo-Huang Yuan, 袁碩璜
• Other Authors: Pei-Wen Li
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/80296590667441792309

博士 === 國立中央大學 === 電機工程學系 === 104 === In this thesis, we investigated the photodetection capability of organic phototransistors (OPTs) with metallic nanoparticles decoration. The main features encompass as follows. First, we investigated the effect of Al2O3/PMMA stack dielectrics on OTFT performance in terms of leakage and depletion capacitance. Compared to the OTFTs with single-layer PMMA, OTFTs with stacked-dielectrics exhibit better leakage-current blocking ability and a lower depletion capacitance thanks to better pentacene crystallinity. Secondly, we investigated the photo energy transfer efficiency enhancement by gold nanoparticles (Au NPs) for OPTs. We elucidated the transfer characteristics of OPTs without and with Au NPs layers under illuminationor not. Au NPs OPTs exhibit dramatic enhancement in drain current under illumination and significant increment in energy transfer efficiency accordingly. The energy transfers efficiency is 10.23 and 18.03% for OPTs with and without Au NPs, respectively. This result indicates that surface plasmon resonance greatly facilities the transfer of photon energy in semiconductor through the enhancement of localized light intensity. Thirdly, we have successful demonstrated that inclusion of Au NPs within Opts is conducive for deep UV detection. The size of Au NPs size is smaller than 10nm by precisely designed deposition process. The responsivity changes from 1.6 to 4.5 A/W when we included the Au NPs into OPTs. Fourthly, we investigated the effect of silver nanoparticles (Ag NPs) size on OPTs photo-detection. As the gate voltage is greater than -20 V, pentacene OTFTs with 2nm-thick Ag-NP decoration exhibited the highest responsivity.