Tuning energy alignment

Besides the stability issues encountered at the solid-liquid interface, its electronic quality defines the efficiency of the system. This encompasses the control of surface recombination but, also, the control of the energy band alignments between light absorbers, interfacial films, and electrocatalysts. Accordingly, two avenues have to be followed (i) the reduction of the surface recombination velocity (compare Eqs. 10,11,14) and (ii) the use of surface- or interface dipoles for band alignment tuning purposes. 

Enhancing Charge Extraction at Electrodes and Tuning Energy Alignment... 

Intensive effort has been devoted to the optimization of CCP structures for improved fluorescence output of CCP-based FRET assays. The inherent optoelectronic properties of CCPs make PET one of the most detrimental processes for FRET. Before considering the parameters in the Forster equation, it is of primary concern to reduce the probability of PET. As the competition between FRET and PET is mainly determined by the energy level alignment between donor and acceptor, it can be minimized by careful choice of CCP and C. A series of cationic poly(fluorene-co-phenylene) (PFP) derivatives (IBr, 9, 10 and 11, chemical structures in Scheme 8) was synthesized to fine-tune the donor/acceptor energy levels for improved FRET [70]. FI or Tex Red (TR) labeled ssDNAg (5 -ATC TTG ACT ATG TGG GTG CT-3 ) were chosen as the energy acceptor. The emission spectra of IBr, 9, 10 and 11 are similar in shape with emission maxima at 415, 410, 414 and 410 nm, respectively. The overlap between the emission of these polymers and the absorption of FI or TR is thus similar. Their electrochemical properties were determined by cyclic voltammetry experiments. The calculated HOMO and LUMO... 

In these wave packet simulations, the molecular axis of the FHF system is assumed to be aligned along the space-fixed axis Z electric field vector. This assumption involves a maximum interaction of the IR and UV laser pulses with the system. Recalling that the time-dependent interaction potential is given by the scalar product of the electric field vector and the dipole vector, i.e. (t) /j, cos 9, it is clear that for field polarizations perpendicular to the molecular axis [9 = 90°) the interaction of the IR laser pulse with the anion vanishes, and for any molecular orientation different from 0= 0° or 180° the interaction is less efficient. Consider now an ensemble of randomly oriented FHF molecules, as in Fig. 4.13(c). Since the UV pulse is tuned to match the energy gap between anion and neutral... 

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