以NFSI有機分子摻雜化學氣相沉積法石墨烯並提升石墨烯/矽-蕭基接面太陽能電池轉換效率

NFSI Doped CVD-Graphene for Enhancing the Efficiency of Graphene-Silicon Schottky Photovoltaics

曾紀洋(Chi-Yang Tseng)

指導教授 ： 陳家俊

國立臺灣師範大學/理學院/化學系/碩士(2012年)

摘要

石墨烯，為碳碳原子之間以sp2鍵鍵結而成的二維結構材料，因為具有許多特殊的物理性質，像是高載子遷移率、高熱傳導性、優異的機械性質及光學性質，因此可望應用在電晶體、透明導電電極、偵測器以及光電元件上。
近年來，許多研究致力於改善以及探索石墨烯的電性，並可望開發於光電元件上的應用。在本篇論文中，我們以化學摻雜的方式摻雜NFSI((C6H5SO2)2NF)分子於石墨烯上。NSFI摻雜後的石墨烯，其電阻值明顯大幅的下降並且還維持著良好的穿透度。在拉曼圖譜中確認NFSI對石墨烯摻雜上的變化，摻雜前後比較，發現G band和2D band偏移分別為1581至 1586 cm-1、2631 至2643cm-1。更進一步了解摻雜前後電性上的改變，從石墨烯電晶體以及霍爾效應量測電性的結果，我們發現石墨烯電洞的載子濃度大幅度上升，證明了NFSI摻雜之石墨烯為P型態摻雜，而載子遷移率的下降主要是因為雜質散射所造成。
此外，我們結合了一層NFSI-石墨烯/n-矽形成蕭基接面太陽能電池做為探討。在這樣的結構元件下，以AM1.5照射所得到的轉換效率可以達到3.56%，與未摻雜前的1.74%提升了2倍左右。接著以電流—電壓、電容—電壓關係量測元件特性，可以發現效率的提升以及開路電壓的增高，主要是因為NFSI提高了石墨烯的載子濃度以及提升了元件系統中的內建電位。

關鍵字

石墨烯 ； 摻雜 ； 蕭基接面太陽能電池

並列摘要

Graphene, a single layer of sp2-bonded carbon atoms, demonstrates many unique physical properties such as high mobility of charge carriers, high thermal conductivity, excellent mechanical and optical properties, so it is expected to be used in transistors, transparent electrodes, sensors and photovoltaic device.
Recently, a lot of effort has been focused on improving electric properties of graphene and exploring the new optoelectronic applications. In this study, monolayer graphene was doped with NFSI ((C6H5SO2)2NF) molecular by using chemical doping method. After modified with NFSI, the conductivity of NFSI-graphene has been increased dramatically and high transmittance of monolayer graphene was still preserved. In Raman spectra, the G and 2D band peak position of NFSI-graphene is shift from 1581 to 1586 cm-1、2631 to 2643cm-1, respectively compared to pristine graphene. Furthermore, from the FET and Hall measurement, we found that the hole carrier density of NFSI-graphene was highly increased in consistent with the result of p-type doping. However, the decreases of mobility of NFSI-graphene was could be attributed to impurity scattering.
Besides, we also demonstrate monolayer NFSI-graphene/n-silicon Schottky-junction solar cells. Under AM1.5 illumination, the NFSI-graphene/n-silicon Schottky device exhibit a higher power conversion efficiency (PCE) of 3.56% than that of pristine-graphene 1.74%. Current-voltage and capacitance-voltage measurement showed that the enhancement of PCE and Voc is due to increases of the device cell’s built-in potential affected by higher carrier density of NFSI-graphene.

並列關鍵字

graphene ； doping ； Schottky-junction solar cells

參考文獻

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