Bis-1,4-[2-(2-oxoindolin-3-ylidene)malononitrile]benzene Derivatives for N-Channel Organic Field Effect Transistors

[[abstract]]有機場效電晶體已經應用於部分的電子產品中，像是傳導器、電子紙和顯示器。有機半導體的材料一直在不斷創新跟進步，有機半導體材料主要又可分P型跟N型兩種，效能方面N型材料的發展比P型材料的發展還晚了許多，N型的材料必須滿足在空氣中穩定的條件。本篇論文雙-2,6-[2-(2-氧代二氫吲哚-3-亞基)丙二腈]苯衍生物(PBIM、PBAIM)當作有機半導體的材料，在結構上接上拉電子基試圖降低最低電子未佔有軌域，以及增加分子的π共軛長度跟的對稱性，有利於電子在分子間的躍遷跟傳遞。再藉由電化學CV跟UV-vis spectra光譜探討苯環上多一個的氮的取代以及不同碳鏈的取代對分子的能階、能隙跟排列所造成的影響，化合物PBIM跟PBAIM的最大吸收波長分別為716.3 nm跟672.8 nm，能隙分別為1.73 eV跟1.89 eV，再利用CV循環伏安法計算最低未佔有電子軌域能階，分別為-3.87 eV跟-4.00 eV，PBIM跟PBAIM兩支材料有滿足空氣穩定(<-3.8 eV)的條件。 為了探討雙-1,4-[2-(2-氧代二氫吲哚-3-亞基)丙二腈]苯衍生物應用於有機場效電晶體效能，分別利用真空蒸鍍跟液相製程(Bar-casting)方式製作元件，再利用AFM跟XRD去探討分子薄膜的型態跟分子間的堆疊方式。 PBIM由於分子結構本身不易受熱，不適用於真空蒸鍍的製程方式，藉由XRD得知分子在基板上沒有任何的結晶訊號，再藉由AFM得知分子的薄膜型態有許多的晶界，以至於無法量測到電性。PBAIM本身結構接上長碳鏈增加溶解度，適用於液相製程，藉由XRD得知分子在基板上有很好的結晶性，再藉由AFM得知分子的薄膜表面有些許的晶界造成薄膜的連續性不佳，以至於無法量測到電性。[[abstract]]In recent decades, organic field-effect transistors(OFETs) has been applied in different products, such as conductor, electronic paper and display monitor. Currently, significant progress in organic semiconductor (OSCs) has been made; however, the overall development of n-types OSCs still lags behind their p-type counterparts, especially in terms of charge transfer performance, ambient stability. In this study, we successfully synthesized Bis-1,4-[2-(2-oxoindolin-3-ylidene)malononitrile]benzene derivatives(PBIM and PBAIM) as OSCs. Its advantage is that the symmetry of the structure and π-conjugation on which can enhance the jump range of electron and the interaction between molecules as well as the charge carrier mobility. In this study, we successfully synthesized Bis-1,4-[2-(2-oxoindolin-3-ylidene)malononitrile]benzene derivatives(PBIM and PBAIM) as OSCs. Its advantage lies in the symmetry of the structure and π-conjugation on which can enhance the jump range of electron and the interaction between molecule improve the charge carrier mobility. The UV-vis spectra optical properties and CV electrochemical could be used to calculate its LUMO energy level and energy gap. The maximum UV-vis absorption of PBIM and PBAIM are 716.3 and 672.8 nm while the energy gap are 1.73 eV and 1.89 eV, respectively. The LUMO value of PBIM and PBAIM are -3.87 eV and -4.00 eV. Furthermore PBIM and PBAIM were beneficial for air-stable N-type OFET. In order to understand the charge transfer properties of PBIM and PBAIM. Firstly, we utilize the vacuum-deposition and solution process (Bar-casting) to developed OSCs. To study the influence of the nitrogen substituent and alkyl chain on the electron-transporting properties of PBIM and PBAIM derivatives, top-contact bottom-gate OFETs.The thin films were characterized by atomic force microscopy (AFM) and X-ray diffraction (XRD) to elucidate the relationships between molecular structure, film morphology and crystallinity. The XRD spectra of PBAIM based film showed diffraction peak indicating good crystallinity, in contrast, XRD analysis of PBIM based film showed no diffraction peak. The AFM image of PBIM and PBAIM showed amorphous nature. Which yield poor carrier transport in PBIM and PBAIM based films.[[note]]碩