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SUMMARY Organic photodetectors based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) blends with indium tin oxide (ITO) modified by phosphonic acid-based self-assembled monolayer (SAM) treatment in a short time are investigated. The mixed SAMs serve to tune the surface free energy and the work function of ITO by varying the blend ratio. The phosphonic acid-based SAM treatment results not only in lowering of the injection barrier at the ITO/organic layer interface but also in the lowering of the contact resistance between ITO and the organic layer, as shown by impedance spectroscopy in P3HT hole-only device with SAMs. P3HT:PCBM device with ITO modified by short treatment time of 1H,1H,2H,2H-perfluorooctane-phosphonic acid exhibits an incident-photon-to-current conversion efficiency of above 50% at -2 V, a high on/off ratio, and improved durability. [ABSTRACT FROM AUTHOR]

Poly(methyl methacrylate) (PMMA) gate dielectric formed using fluorine‐based solvent, CF3CH2OCF2CHF2 (AGC, AE‐3000), is useful to prevent mixing of the dielectric layer with the emissive layer for top‐gated organic light‐emitting transistor (OLET) device fabrication. The device performance of OLETs based on a poly(p‐phenylene vinylene) derivative, Super Yellow, is improved because of the fabrication without intermixing. For an OLET with Pt‐tetraphenyltetrabenzoporphyrin [Pt(tpbp)] doped in poly(alkylfluorene), a near‐infrared emission from Pt(tpbp) and a relatively high external quantum efficiency of approximately 1% are achieved. This device fabrication method opens perspectives in the development of the damage‐free fabrication processes in printed top‐gated OLETs. [ABSTRACT FROM AUTHOR]

Highlights: [•] ITO modified by phosphonic acid-based self-assembled monolayer (SAM). [•] 1H,1H,2H,2H-Perfluorooctanephosphonic acid (FOPA) is used as SAM. [•] Lowering of the injection barrier at the ITO/organic layer interface. [•] Lowering of the contact resistance between ITO and the organic layer. [•] Polymer photodetector with FOPA exhibits high efficiency and high on/off ratio. [ABSTRACT FROM AUTHOR]

Highlights: [•] Cs2CO3:conjugated polyelectrolyte blended interfacial layer is used. [•] Improved electron injection from Ag electrode is achieved. [•] Solution-processed Ag cathode is fabricated using Ag nano-ink. [•] Interfacial layer prevents Ag nano-ink from penetrating into emissive layer. [•] Solution-processed device using Ag nano-ink exhibits luminance (10,000cd/m2). [Copyright &y& Elsevier]

Abstract: Properties of solution-processed organic photodetectors with iridium (Ir) complexes doped in fluorene-type conjugated polymer, poly(dioctylfluorene-co-benzothiadiazole) [F8BT] as a host were investigated. F8BT devices had blue sensitivity. Ir complexes as triplet materials can enhance the incident-photon-to-current conversion efficiency (IPCE) of the devices when their triplet levels are lower than the lowest excited singlet states (S1) of the host and higher than the lowest excited triplet states (T1) of the host. A bilayer F8BT device utilizing solution-processable starburst molecular and tris(2-phenylpyridine)iridium(III) [Ir(ppy)3] as a hole transporting layer and a dopant, respectively, showed larger photocurrent than an non-doped bilayer device under high applied voltage. For the bilayer device with Ir(ppy)3, a cut-off frequency of more than 10MHz was observed under forward bias of 5V and clear response pulses at 10MHz were received using a sinusoidal modulated laser light illumination. [Copyright &y& Elsevier]