Energy level alignment at C60/DTDCTB/PEDOT:PSS interfaces in organic photovoltaics

Jisu Yoo, Kwanwook Jung, Junkyeong Jeong, Gyeongho Hyun, Hyunbok Lee, Yeonjin Yi

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7 Citations (Scopus)


The electronic structure of a narrow band gap small molecule ditolylaminothienyl–benzothiadiazole–dicyanovinylene (DTDCTB), possessing a donor-acceptor-acceptor configuration, was investigated with regard to its application as an efficient donor material in organic photovoltaics (OPVs). The interfacial orbital alignment of C60/DTDCTB/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was determined using in situ ultraviolet photoelectron and inverse photoelectron spectroscopic methods. The ionization energy and electron affinity values of DTDCTB were measured to be 5.27 eV and 3.65 eV, respectively, and thus a very small transport gap of 1.62 eV was evaluated. Large band bending of DTDCTB on PEDOT:PSS was observed, resulting in a low hole extraction barrier. Additionally, the photovoltaic gap between the highest occupied molecular orbital level of the DTDCTB donor and the lowest unoccupied molecular orbital level of the C60 acceptor was estimated to be 1.30 eV, which is known to be the theoretical maximum open-circuit voltage in OPVs employing the C60/DTDCTB active layer. The unique electronic structures of DTDCTB contributed toward the recently reported excellent power conversion efficiencies of OPVs containing a DTDCTB donor material.

Original languageEnglish
Pages (from-to)41-46
Number of pages6
JournalApplied Surface Science
Publication statusPublished - 2017 Apr 30


All Science Journal Classification (ASJC) codes

  • Surfaces, Coatings and Films

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