Dae Sung Chung

High-mobility solution-processed all-inorganic solid state nanocrystal (NC) transistors with low operation voltage and near-zero hysteresis are demonstrated using high-capacitance ZrO(x) and hydroxyl-free Cytop gate dielectric materials. The use of inorganic capping ligands (In(2)Se(4)(2-) and S(2-)) allowed us to achieve high electron mobility in the arrays of solution-processed CdSe nanocrystals. We also studied the hysteresis behavior and switching speed of NC-based field effect devices. Coll

Abstract High‐performance and high‐reliability photodiodes are demonstrated by using α‐CsPbI 3 perovskite nanocrystals (NCs) phase‐stabilized with a low‐temperature solution‐treated active layer. In addition to the high charge mobility, the high absorption coefficient, and IR‐blind characteristics of the perovskite material, the defect‐tolerant nature of α‐CsPbI 3 perovskite NCs are combined to realize hysteresis‐free and high detectivity photodiodes. To further minimize interface defects origin

Developing high-performance gas sensors based on polymer field-effect transistors (PFETs) requires enhancing gas-capture abilities of polymer semiconductors without compromising their high charge carrier mobility. In this work, cohesive energies of polymer semiconductors were tuned by strategically inserting buffer layers, which resulted in dramatically different semiconductor surface morphologies. Elucidating morphological and structural properties of polymer semiconductor films in conjunction

The theoretical optoelectronic properties of chalcogenide perovskites (e.g., BaZrS3) are as good as those of halide perovskites (e.g., CH3NH3PbI3). But the fabrication of optoelectronic devices is rarely reported, mainly because researchers still do not know how to prepare good quality thin films of chalcogenide perovskites. Here, we report colloidal BaZrS3 nanocrystals (NCs, 40-60 nm) and their solution processed thin film transistors. BaZrS3 NCs are first prepared using a solid-state synthesis

A series of new anthracene based semiconductors are designed and synthesized. By substituting appropriate acenes at the 2,6-positions of triisopropylsilylethynyl anthracene (NMR, IR, DSC and TGA spectra and crystallographic information of TIPSAntBT and TIPSAntNa), two different derivatives were prepared. Especially, TIPSAntNa (naphthalene as a side group) showed superior performance when it was used as channel material. A hole mobility as high as 3.7 cm2 V−1 s−1 was obtained from single crystal

We have synthesized a new p-type polymer, poly[(1,2-bis-(2′-thienyl)vinyl-5′,5′′-diyl)- alt -(9,9-dioctyldecylfluorene-2,7-diyl] (PTVTF), via a Suzuki coupling reaction. PTVTF was found with UV–vis absorption spectroscopy, GIXD, AFM, and NEXAFS to be an ‘annealing-freeʼ amorphous polymer. Despite its amorphous nature, our time-of-flight measurements demonstrate that PTVTF is a good hole transport material with an intrinsic hole mobility of 2 × 10 −4 cm 2 /Vs, which is comparable to those of crys

Abstract Photomultiplication‐type organic photodetectors (PM‐OPDs) with high external quantum efficiency (EQE) of over 100% are attracting increasing attention due to their potential importance in detecting weak incident light. Considering that the gain of PM‐OPD is determined by the ratio of carrier lifetime over carrier transit time, a systematic study on the effect of the end‐functionalization of a new extended aromatic fused‐ring non‐fullerene acceptor (NFA) on the carrier trap/transit time

Cu2BaSnS4 (CBTS) is an emerging earth-abundant and environmentally benign semiconductor. However, there has been no prior report of colloidal CBTS nanocrystals. Here we developed a colloidal synthesis of CBTS nanocrystals by rational design. Photophysical properties of these nanocrystals are elucidated using photoluminescence and ultrafast transient absorption spectroscopy. Finally, thin films of CBTS nanocrystals grown at room temperature are used as the hole transport layer (HTL) in an organic

Poly(5′,5′′-bithiophene-alt-2,6-[(1,5-didecyloxy)naphthalene]) (PBDN) was synthesized from 2,6-dibromo-l,5-didecyloxynaphthalene and 1,1′-[2,2′-bithiophene]-5,5′-diylbis[1,1,1-trimethylstannane] and was used as the active layer in organic thin-film transistors (OTFTs) and organic photovoltaic cells (OPVs). The obtained PBDN was soluble in organic solvents such as chloroform, chlorobenzene, and toluene and had a weight-averaged molecular weight of 9100, with a polydispersity index of 1.31. The ph

Effects of fluorine substitution of small molecular semiconductor on charge transport and photovoltaic properties are systematically studied.

Abstract A photomultiplication‐type organic photodiode (PM‐OPD), where an electric double layer (EDL) is strategically embedded, is demonstrated, with an exceptionally high external quantum efficiency (EQE) of 2 210 000%, responsivity of 11 200 A W −1 , specific detectivity of 2.11 × 10 14 Jones, and gain–bandwidth product of 1.92 × 10 7 Hz, as well as high reproducibility. A polymer electrolyte, poly(9,9‐bis(3′‐( N , N ‐dimethyl)‐ N ‐ethylammoinium‐propyl‐2,7‐fluorene)‐ alt ‐2,7‐(9,9‐dioctylflu

A thin film planar heterojunction organic photodetector (PHJ-OPD) is demonstrated. Different from a conventional sensitizer-doped photodetector, the limited spatial distribution of sensitizer in a PHJ-OPD enables significantly reduced thickness of the active layer without allowing the formation of unnecessary trap sites and electron percolation pathways. As a result, peak external quantum efficiency (EQE) of 120 700% and detectivity over 10 13 Jones are demonstrated with thin active layer thickn

A summary of color selective organic photodiodes in accordance with various color selection mechanisms is presented.

To elucidate the origin of the high field-effect mobility (≈0.02cm2∕Vs) of amorphous poly[(1,2-bis-(2′-thienyl)vinyl-5′,5″-diyl)-alt-(9,9-dioctyldecylfluorene-2,7-diyl], we investigated the current density–voltage (J-V) and mobility–voltage (μ-V) relationships as a function of temperature. By using the power law model and the Gaussian hopping model, we determined a characteristic trap energy of 67meV, an energetic disorder parameter of 64meV, and a total trap density of 2.5×1016cm−3, comparable