A New Tetracyclic Lactam Building Block for Thick, Broad-Bandgap Photovoltaics

Renee Kroon, Amaia Mendaza, Scott Himmelberger, Jonas Bergqvist, Olof Backe, Gregoria Faria, Feng Gao, Abdulmalik Obaid, Wenliu Zhuang, Desta Gedefaw, Eva Olsson, Olle Inganas, Alberto Salleo, Christian Muller, Mats R. Andersson

    Research output: Contribution to journalArticlepeer-review

    67 Citations (Scopus)


    A new tetracyclic lactam building block for polymer semiconductors is reported that was designed to combine the many favorable properties that larger fused and/or amide-containing building blocks can induce, including improved solid-state packing, high charge carrier mobility, and improved charge separation. Copolymerization with thiophene resulted in a semicrystalline conjugated polymer, PTNT, with a broad bandgap of 2.2 eV. Grazing incidence wide-angle X-ray scattering of PTNT thin films revealed a strong tendency for face-on π-stacking of the polymer backbone, which was retained in PTNT:fullerene blends. Corresponding solar cells featured a high open-circuit voltage of 0.9 V, a fill factor around 0.6, and a power conversion efficiency as high as 5% for >200 nm thick active layers, regardless of variations in blend stoichiometry and nanostructure. Moreover, efficiencies of >4% could be retained when thick active layers of ∼400 nm were employed. Overall, these values are the highest reported for a conjugated polymer with such a broad bandgap and are unprecedented in materials for tandem and particularly ternary blend photovoltaics. Hence, the newly developed tetracyclic lactam unit has significant potential as a conjugated building block in future organic electronic materials.

    Original languageEnglish
    Pages (from-to)11578-11581
    Number of pages4
    JournalJournal of The American Chemical Society
    Issue number33
    Publication statusPublished - 20 Aug 2014


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