888491-16-5Relevant articles and documents
Tuning Electronic and Morphological Properties for High-Performance Wavelength-Selective Organic Near-Infrared Cavity Photodetectors
Vanderspikken, Jochen,Liu, Quan,Liu, Zhen,Vandermeeren, Tom,Cardeynaels, Tom,Gielen, Sam,Van Mele, Bruno,Van den Brande, Niko,Champagne, Beno?t,Vandewal, Koen,Maes, Wouter
, (2021/11/22)
Incorporation of compact spectroscopic near-infrared (NIR) light detectors into various wearable and handheld devices opens up new applications, such as on-the-spot medical diagnostics. To extend beyond the detection window of silicon, i.e., past 1000?nm, organic semiconductors are highly attractive because of their tunable absorption. In particular, organic NIR wavelength-selective detectors have been realized by incorporating donor:acceptor thin films, exhibiting weak intermolecular charge-transfer (CT) absorption, into an optical microcavity architecture. In this work, the alkyl side chains of the well-known PBTTT donor polymer are replaced by alkoxy substituents, hereby redshifting the CT absorption of the polymer:PC61BM blend. It is shown that the unique fullerene intercalation features of the PBTTT polymer are retained when half of the side chains are altered, hereby maximizing the polymer:fullerene interfacial area and thus the CT absorption strength. This is exploited to extend the detection range of organic narrow-band photodetectors with a full-width-at-half-maximum of 30–38?nm to wavelengths between 840 and 1340?nm, yielding detectivities in the range of 5 × 1011 to 1.75 × 1010 Jones, despite the low CT state energy of 0.98?eV. The broad wavelength tuning range achieved using a single polymer:fullerene blend renders this system an ideal candidate for miniature NIR spectrophotometers.
Benzo[1,2-b:4,5-b']dithiophene-based copolymers applied in bottom-contact field-effect transistors
Leenen, Mark A.M.,Cucinotta, Fabio,Pisula, Wojciech,Steiger, Jürgen,Anselmann, Ralf,Thiem, Heiko,De Cola, Luisa
experimental part, p. 3099 - 3107 (2011/10/31)
Three copolymers of benzo[1,2-b:4,5-b']dithiophene and 3,3'-bis(alkyl)-5,5'-bithiophene (dodecyl, tetradecyl and hexadecyl side chains) have been synthesized through Stille copolymerization. The polymers have number-average molecular weights over 20 kg/mol, are well-packed in the bulk and thin film, and possess an ionization potential of -5.1 eV in thin film, which offers stability versus oxidation in environmental conditions. The thin film packing of the polymer with dodecyl side chains leads to an excimeric emission upon excitation, which is not observed for longer side chain lengths. The presence of the dimers responsible for this excimer formation results in a device performance improvement as well. Field-effect transistors fabricated from these copolymers have On/Off ratios >107, equal saturation and linear hole mobilities above 10-2 cm2/Vs, almost no hysteresis and turn-on voltages around 0 V in bottom-contact devices.
