0000000000733000
AUTHOR
Jürgen Parisi
Ligand removal from soluble CdTe nanocrystals evidenced by time-resolved photoluminescence spectroscopy
We present experimental studies on the effect of pyridine treatment on the optical properties of ligand-stabilized colloidal CdTe nanocrystals. We demonstrate, by quasi-stationary and time-resolved photoluminescence (PL) spectroscopy, a drastic reduction in the PL lifetime and a concomitant decrease in the PL yield by more than 90% when dissolving the nanocrystals in pyridine. The pyridine solvent efficiently removes the ligand shell and thus enables a rapid energy transfer from the quantum dot to optically dark surface states or into the solvent. The demonstrated removal of the ligand shell is a key step towards integrating such CdTe nanocrystals in hybrid organic/inorganic nanocomposites,…
Design, synthesis and photovoltaic properties of [60]fullerene based molecular materials
Abstract The possibility to use new organic semiconductor materials, in place of silicon wafers, in the fabrication of photovoltaic devices on substrates offer the prospect of lower manufacturing costs, particularly for large area applications. Thus, one of the most promising areas in fullerene research involves its potential application, mixed with conjugated polymers, in mimicking photosynthesis and in the related solar energy conversion. The tendency to phase segregation in blends of C60 derivatives and conjugated polymers has to be optimized to improve both charge photogeneration and transport in photovoltaic devices. In order to optimize device performances, a great deal of work has be…
Femtosecond up-conversion technique for probing the charge transfer in a P3HT : PCBM blend via photoluminescence quenching
We report on an experimental study of the charge transfer dynamics in a P3HT : PCBM blend by means of a femtosecond fluorescence up-conversion technique. Using two-photon excitation we probe the exciton dynamics in P3HT and a P3HT : PCBM blend with a weight ratio of 1 : 1 at excitation densities of up to 6 × 1018 cm−3. In both samples we find strongly nonexponential decay traces compatible with (i) diffusion-limited exciton–exciton annihilation and (ii) diffusion-limited donor–acceptor charge transfer in the polymer blend. Additionally, our results indicate that in the P3HT : PCBM blend about 50% of the photogenerated excitons undergo a prompt charge transfer process on a time scale of abou…