Characterization of the contact between TiO2 and PbS quantum dots

The synthetic procedure of the growth of one semiconductor material (PbS) on a seed of another (TiO2) have been developed. The contact between TiO2 and PbS quantum dots was characterized by optical absorption and fluorescence. The dramatic increase of the bandgap of PbS (ΔEg=1.5 eV) was observed after precipitation of PbS in the colloidal solution of TiO2. The positions of the lowest empty energy level of TiO2 and PbS single quantum dots as well as TiO2-PbS composite were determined by pulse radiolysis technique. The contact between TiO2 and PbS quantum dots leads to the transfer of electrons from PbS to TiO2.International Conference on Microelectronics : September 12-14, Niš, 199

Realizing Solution-Phase Room Temperature Quantum Coherence in a Tetrathiafulvalene-Based Diradicaloid Complex

Molecular electron spins are promising candidates as scalable and tunable qubits but often suffer from air sensitivity or other undesirable decomposition pathways. Furthermore, significant spin‒lattice relaxation and nuclear spin-mediated decoherence limit their applications. While significant advances in the synthesis of new molecular electron spin qubit candidates have led to improved coherence lifetimes, one key question is whether coherence can be maintained under conditions relevant for employment as quantum sensors, for instance in solution and at room temperature for sensing in biological systems. Here we report a tetrathiafulvalene-based molecular qubit candidate with spin centered on a nuclear spin-free bridging ligand. This unique air and water-stable scaffold exhibits a long spin decoherence time of hundreds of nanoseconds at ambient temperatures and in nuclear spin-rich protonated solvents. These results distinguish this system as a promising candidate for the development of novel room temperature, solution-phase quantum sensing technologies, and suggest that molecular electron spin qubits can be ideal candidates for these applications

Solar cells Improved Hybrid Solar Cells via in situ UV Polymerization

One approach for making inexpensive inorganic-organic hybrid photovoltaic (PV) cells is to fill highly ordered TiO 2 nanotube (NT) arrays with solid organic hole conductors such as conjugated polymers. Here, a new in situ UV polymerization method for growing polythiophene (UV-PT) inside TiO 2 NTs is presented and compared to the conventional approach of infiltrating NTs with pre-synthesized polymer. A nanotubular TiO 2 substrate is immersed in a 2,5-diiodothiophene (DIT) monomer precursor solution and then irradiated with UV light. The selective UV photodissociation of the CÀI bond produces monomer radicals with intact p-ring structure that further produce longer oligothiophene/PT molecules. Complete photoluminescence quenching upon UV irradiation suggests coupling between radicals created from DIT and at the TiO 2 surface via a charge transfer complex. Coupling with the TiO 2 surface improves UV-PT crystallinity and p-p stacking; flat photocurrent values show that charge recombination during hole transport through the polymer is negligible. A non-ideal, backside-illuminated setup under illumination of 620-nm light yields a photocurrent density of %5 mA cm 2 -surprisingly much stronger than with comparable devices fabricated with polymer synthesized ex situ. Since in this backside architecture setup we illuminate the cell through the Ag top electrode, there is a possibility for Ag plasmon-enhanced solar energy conversion. By using this simple in situ UV polymerization method that couples the conjugated polymer to the TiO 2 surface, the absorption of sunlight can be improved and the charge carrier mobility of the photoactive layer can be enhanced