We report photovoltaic devices based on composites of a branched nanoheterostructure containing a CdTe core and CdSe arms, CdTe(c)-CdSe(a), combined with either poly(3-hexylthiophene), P3HT, or poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)], PCPDTBT, with solar power conversion efficiencies of 1.2% and 1.8%, respectively. A comparison with previously reported composite devices of a related branched nanoheterostructure: CdSe(c)-CdTe(a) reveals an improved device performance that is attributed to a better electron percolation pathway provided by the dominant, higher electron affinity CdSe arms of the nanoheterostructures.
Narrow and symmetric emission spectrum, continuous excitation spectrum, high quantum yields and resistance to photobleaching are outstanding advantages semiconductor nanoparticles exhibit ideally compared to conventional fluorescent dyes. However, it is still a challenge to replace existing organic fluorophores and develop a tool for imaging and site-specific drug delivery. In this presentation, we demonstrate the chemistry and spectroscopy of homogeneously alloyed nanocrystals and nanocrystal-doped protein microspheres, emitting the IR and near-infra red as tools for bio-imaging, and drug delivery, respectively. In addition, nanoparticles are studied as energy donors to photosensitizer phthalocyanine dyes, which have proven potential for photodynamic therapy.
Photodynamic therapy (PDT) is an emerging therapy for cancer treatment that shows the greater selectivity towards the malignant cells. Semiconductor nanoparticles are a novel class of photosensitizers with properties that are not easily available with conventional PDT reagents. Their potential properties such as improved luminescence, resistance to photobleaching, and the possibility to modify the surface chemically make them suitable candidates for PDT. In this report, we discuss the synthesis of ternary CdSe<sub>1-x</sub> Tex nanoparticles along with well known CdSe QDs and their potential in generating the singlet oxygen state by Foerster Resonance Energy Transfer (FRET) to a PDT reagent or by direct triplet-triplet energy transfer to molecular oxygen.