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A new solution processable star-shaped organic molecule S(TPA-BT) has been synthesized for application in organic solar cells (OSCs). The properties and structures of S(TPA-BT) and a related linear molecule L(TPA-BT) were studied, including UV-visible spectroscopy, hole charge mobility, and theoretical calculated geometry and electronic properties. S(TPA-BT) film shows a broader and stronger absorption band in the range of 440–670 nm, lower band gap of 1.86 eV, higher hole mobility of 4.71 × 10−5 cm2 V−1 s−1 and better film-forming properties compared with those of L(TPA-BT) film. ITO/PEDOT:PSS/S(TPA-BT) or L(TPA-BT):PCBM/Ba/Al bulk-heterojunction OSCs were fabricated with S(TPA-BT) or L(TPA-BT) as donor material. The power conversion efficiency (PCE) of an OSC based on a blend of S(TPA-BT) and PCBM (1 : 3, w/w) reached 1.33% under A.M. 1.5 illumination, 100 mW cm−2, with a short-circuit current density (JSC) of 4.18 mA cm−2, an open circuit voltage of 0.81 V, and a fill factor of 39%. The PCE of 1.33% and Jsc of 4.18 mA cm−2 are among the highest values reported so far for solution processable OSCs. [ABSTRACT FROM AUTHOR]

Poled polymers are currently of great interest in second-order nonlinear optical (NLO) applications such as electro-optic (EO) modulation, optical switching, etc. The EO active chromophores doped in polymer matrices generally have large dipole moment. The strong electrostatic interaction between molecular dipoles causes orientation relaxation after poling, decrease of poling efficiency, phase separation, and etc. at high doping concentration. A new type of NLO chromophore with low ground-state dipole moment has been designed and synthesized. It was doped in PMMA polymer matrix. The electrostatic interaction between chromophore molecules in this doped film is reduced greatly. This provides a way to increase the doping level in guest-host poled polymer system. At a very high loading level of 52% wt. (N = 6.41 × 1020/cm3), which is over 2 times of the theoretically predicated value for the spherical shape molecules, reasonable film quality and dipole orientation stability have been achieved. [ABSTRACT FROM AUTHOR]

The strategy of introducing the chromophores with low ground state dipole moment had been discussed to overcome the effect of the electrostatic interaction between the chromophores in the poled polymer films on its nonlinearity. As a result, the effective nonlinear optical coefficient d[sub 33] of the poled films, containing the chromophores with μ[sub g] in the range of 3.5–5.5 D, will enhance at least 15%, even over 30%, compared to that of 7.5 D if the first hyperpolarizabilities (β) of chromophores are in the same magnitudes. And, under the above assumption, the same level of the d[sub 33] could even be achieved by utilizing the chromophores with μ[sub g] as low as 2.2 D. [ABSTRACT FROM AUTHOR]

Reports on three reactions of C60 and azomethine ylides obtained in situ from ketones and ...-aminoacids. Two reasons why the reactions were selected; Synthesis of fulleropyrrolidine derivative using fullerene, ketone and ...-aminoacid; Discussion on findings of study.

Long and flexible crystalline CdS nanowire ropes were synthesized in bulk quantities via a simple aqueous chemical growth route, which has previously been successful for the growth of short CdS nanorods. The as-grown CdS nanoropes exhibit a unique helically twisted structural feature, as confirmed by both microscopic observation and circular dichroism spectroscopic characterization. The nucleation and growth kinetics of these related CdS one-dimensional(1D) nanocrystals was investigated by monitoring the temporal evolution of the UV-visible spectrum. It was found that cadmium and sulfide monomers were first nucleated out as “magic number” CdS nanoclusters in the initial nucleation stage, and then grew to regular sized CdS 1D nanocrystals during the subsequent Ostwald ripening process. [ABSTRACT FROM AUTHOR]

In this Letter, we report on the temperature-dependent conductivity and current-voltage curve of a single CdS nanowire, which was synthesized by a simple aqueous chemical growth method. A pair of platinum microleads was fabricated on the single CdS nanowire by focused ion-beam deposition. The room-temperature conductivity and the band gap of the single CdS wire are 0.82 Ω-1 cm-1 and 0.055 eV, respectively. When the applied electric field is larger than 1090 V cm-1, the CdS nanowire shows a nonlinear I-V curve at room temperature. [ABSTRACT FROM AUTHOR]

Photoinduced charge transfer between a conjugated polymer and C60 and the related processes were investigated in dilute solutions. The substantial fluorescence quenching is correlated with the efficient exciton diffusion within the polymer chains, according to which a sphere-of-action mechanism is proposed. An emissive exciplex was found formed between the conjugated polymer and fullerene in a nonpolar solvent, indicating the occurrence of a photoinduced partial charge transfer process. The low-energy sites in the polymer are believed to play a crucial role in the partial charge transfer. The asymmetry of the exciplex provides a method for evaluating the tendency of photoinduced charge separation between the donor and the acceptor. This method allows screening candidates for photovoltaic applications. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Demonstrates the optical and electroluminescence (EL) properties of light-emitting diodes on an alternating copolymer containing triphenylamine and phenylene units. Observation of EL in semiconducting conjugated polymer; Synthesis of the copolymer using the Horner reaction; Photoluminescence properties.