利用掃描穿隧顯微鏡量測P3HT／PCBM混摻太陽能電池的界面電子特性

Cross-Sectional Nanoscale Morphology and Interfacial Band Mapping of Phased-Separated Polymer/Fullerene Hybrid Solar Cells by Scanning Tunneling Microscopy

施敏權(Min-Chuan Shih) ； 黃柏超(Bo-Chao Huang) ； 林志誠(Chih-Cheng Lin) ； 李紹先(Shao-Sian Li) ； 陳信安(Hsin-An Chen) ； 邱雅萍(Ya-Ping Chiu) ； 陳俊維(Chun-Wei Chen)

《真空科技》 27卷2期 (2014/06) Pp. 46-50

摘要

本研究藉由剖面式掃描穿隧顯微鏡（Cross-Sectional Scanning Tunneling Microscope, XSTM）直接觀察及量測有機薄膜poly(3-hexylthiophene)(P3HT)以及[6,6]-phenyl C61 butyric acid methyl ester（PCBM）的界面。此方法能直接觀察到電子施體P3HT與受體PCBM間，根據位置所呈現出的能帶結構，並可達原子級的空間解析度。使用剖面式掃描穿隧顯微鏡獨特的優勢是能直接在太陽能電池異質接面（Bulk Heterojunction, BHJ）上同時量測到垂直形貌高度及所對應區域的電子特性，直接觀測到兩電極間隨位置變化的能態密度大小，提供了原子級的視野。這對於太陽能電池中電荷產生、電子傳輸及收集電荷的效率是重要的關鍵。

關鍵字

聚合物／富勒烯混摻太陽能電池 ； 異質接面 ； 能帶圖像化 ； 界面 ； 掃描穿隧式顯微鏡

並列摘要

Using cross-sectional scanning tunneling microscope (XSTM) with samples cleaved in situ in an ultrahigh vacuum chamber, this study demonstrates the direct visualization of high-resolution interfacial band mapping images across the film thickness in an optimized bulk heterojunction polymer solar cell consisting of nanoscale phase segregated blends of poly (3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester(PCBM). We were able to achieve the direct observation of the interfacial band alignments at the donor (P3HT)-acceptor (PCBM) interfaces and at the interfaces between the photoactive P3HT: PCBM blends and the poly (3, 4-ethylenedioxythiophene) poly (styrenesulfonate) (PEDOT: PSS) anode modification layer with an atomic-scale spatial resolution. The unique advantage of using XSTM to characterize polymer/fullerene bulk heterojunction solar cells allows us to explore simultaneously the quantitative link between the vertical morphologies and their corresponding local electronic properties. This provides an atomic insight of interfacial band alignments between the two opposite electrodes, which will be crucial for improving the efficiencies of the charge generation, transport, and collection and the corresponding device performance of polymer solar cells.

並列關鍵字

Polymer/Fullerene Hybrid Solar Cells ； Bulk Heterojunction ； Band Mapping ； Interface ； Scanning Tunneling Spectroscopy