利用金奈米粒子之侷域性表面電漿效應提升有機太陽能電池元件特性

Abstract

此論文主旨為運用化學合成法製備出具有表面電漿共振(LSPR)特性的金奈米粒子，並探討其共振波長與材料結構。我們利用其特殊光學性質，製備出三種不同結構的電漿子有機太陽能電池元件，研究不同金奈米結構的LSPR效應提升元件光吸收機制，以及探討最佳的電漿子元件結構。 我們分別用水熱法、晶種成長法製備出八面體金奈米粒子及金奈米柱，分別摻入元件PEDOT:PSS層中，製備出第一種有機電漿子元件，我們利用UV-visible分析得知，摻有金奈米粒子的元件可提升元件主動層的吸光，使元件效率從4.02 %提升至4.31 %。第二種有機電漿子元件結構為在主動層與陰極間蒸鍍一層金奈米島狀物薄膜(Au nanoislands)，藉由其特殊的LSP效應使元件效率提升從4.02 %增加至4.65 %。最後，我們結合第一種及第二種電漿子元件，設計出有雙層金奈米結構的第三種有機電漿子元件(PEDOT: Au &在主動層與陰極間加入Au nanoislands)，由於成功的結合了兩種LSPR效應而效率最高，最佳效率達4.84 % (較有機元件提升了約20.4 %)。 摻入金奈米粒子於有機太陽能電池中，所引發的LSPR效應造成了光散射以及局佈電場提升現象，順利的使入射光trap於元件主動層中，使有效光路徑增加，提升激子產生率及元件光電流進而使效率提升。

In the purpose of this thesis, we investigated the device characteristics of organic photovoltaics (OPVs) incorporating Au nanoparticles (NPs) utilizing different methods in chemical synthesis that possess the property of localized surface plasmon resonance (LSPR) as well as probed the wavelength of LSPR and the structure for Au NPs. We utilized the special optical properties of Au NPs in LSPR to manufacture three kinds of plasmonic OPVs in the different structures of devices and observed the effects of LSPR for improving the optical absorption. First, we synthesized two kinds of nanostructures in shape for Au NPs to apply in OPV devices, one is octahedral NPs, another is nano-rod NPs. Plasmonic OPV devices by blending Au octhahedral NPs into the PEDOT:PSS layer processed the performance of achievement 4.31% (enhanced 7%). Second, we deposited an Au nano-island film through the thermal evaporation onto the P3HT active layer to observe the PCE of OPV devices. The PCE increased from 4.02% to 4.65% (enhanced 15.7%) by introducing Au nanoislands between P3HT active layer and Al cathode. Finallly, the fabricated plasmonic P3HT-based OPV devices (device structure: ITO/PEDOT:Au NPs/P3HT:PCPM/Au nanoislands/Al) compare with neat P3HT:PCBM devices, the PCE of plasmonic OPVs was improved from 4.02% to 4.84% (enhanced 20.4%). According to the optical and electrical analysis, LSPR enhanced the light absorption efficiency may result from two possible ways that optical path length increases by scattering effect and inducing a strong near-field to enhance the absorption of the active layer. The experimental results suggest a guideline for optimizing the plasmonic OPV structures with regard to their influence on the device properties.