Surface templating via self-assembly of hydrogen-bonded molecular networks is a rapidly developing bottom-up approach in nanotechnology. Using the melamine-PTCDI molecular system as an example we show theoretically that the network stability in the parameter space of temperature versus molecular coupling anisotropy is highly restricted. Our kinetic Monte Carlo simulations predict a structural stability diagram that contains domains of stability of an open honeycomb network, a compact phase, and a high-temperature disordered phase. The results are in agreement with recent experiments, and reveal a relationship between the molecular size and the network stability, which may be used to predict an upper limit on pore-cavity sizes.

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A model of dispersive exciton transport has been developed for a medium with exciton energy levels randomly distributed in both space and energy scale. For a boxcar density of states of excitons an analytical solution is given describing the exciton density as a function of time and the proximity to the exciton quenching interfaces. The model parameters, such as exciton lifetime, effective number of exciton energy levels within inhomogeneously broadened density of states, and hopping distance and hopping rate constants, could be determined using time-resolved photoluminescence data. The developed model is verified via comparison with experimental data on the time-dependent photoluminescence decay of the conjugated polymer MEH-PPV and on the spectrum of internal quantum efficiency of the heterojunction photovoltaic device based on the MEH-PPV/ TiO 2 nanostructure.

The optical properties of mixed crystals CdTel -x-n/SexSn/ andZnTe1 -,-ySe,Sy are investigated by methods of far infrared spectroscopy. Different types of transformation of the vibrational spectra of these solid solutions with composition are found. The longitudinal and transverse optical vibration frequencies are calculated theoretically by means of a unit cellversion of the random element isodisplacement model. The calculations are in satisfactory agreement with the experimental results. The reflection spectra peculiarities with mixed crystal disordering are discussed.