Band-Tail Transport of CuSCN: Origin of Hole Extraction Enhancement in Organic Photovoltaics

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• 作者：Minju Kim ; Soohyung Park ; Junkyeong Jeong ; Dongguen Shin ; Jimin Kim ; Sae Hee Ryu ; Keun Su Kim ; Hyunbok Lee ; Yeonjin Yi
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：July 21, 2016
• 年：2016
• 卷：7
• 期：14
• 页码：2856-2861
• 全文大小：375K
• 年卷期：0
• ISSN：1948-7185

文摘

Copper thiocyanate (CuSCN) is known as a promising hole transport layer in organic photovoltaics (OPVs) due to its good hole conduction and exciton blocking abilities with high transparency. Despite its successful device applications, the origin of its hole extraction enhancement in OPVs has not yet been understood. Here, we investigated the electronic structure of CuSCN and the energy level alignment at the poly(3-hexylthiophene-2,5-diyl) (P3HT)/CuSCN/ITO interfaces using ultraviolet photoelectron spectroscopy. The band-tail states of CuSCN close to the Fermi level (E_F) were observed at 0.25 eV below the E_F, leading to good hole transport. The CuSCN interlayer significantly reduces the hole transport barrier between ITO and P3HT due to its high work function and band-tail states. The barrier reduction leads to enhanced current density–voltage characteristics of hole-dominated devices. These results provide the origin of hole-extraction enhancement by CuSCN and insights for further application.