TY  - JOUR
A1  - Devi, Lekshmi Sudha
A1  - Al-Suti, Mohammed K.
A1  - Dosche, Carsten
A1  - Khan, Muhammad S.
A1  - Friend, Richard H.
A1  - Köhler, Anna
T1  - Triplet energy transfer in conjugated polymers : I. Experimental investigation of a weakly disordered compound
N2  - Efficient triplet exciton emission has allowed improved operation of organic light-emitting diodes (LEDs). To enhance the device performance, it is necessary to understand what governs the motion of triplet excitons through the organic semiconductor. Here, we have investigated triplet diffusion using a model compound that has weak energetic disorder. The Dexter-type triplet energy transfer is found to be thermally activated down to a transition temperature T- T, below which the transfer rate is only weakly temperature dependent. We show that above the transition temperature, Dexter energy transfer can be described within the framework of Marcus theory. We suggest that below T-T, the nature of the transfer changes from phonon-assisted hopping to quantum-mechanical tunneling. The lower electron-phonon coupling and higher electronic coupling in the polymer compared to the monomer results in an enhanced triplet diffusion rate.
Y1  - 2008
ER  - 
TY  - JOUR
A1  - Hille, Carsten
A1  - Berg, Maik
A1  - Bressel, Lena
A1  - Munzke, Dorit
A1  - Primus, Philipp
A1  - Löhmannsröben, Hans-Gerd
A1  - Dosche, Carsten
T1  - Time-domain fluorescence lifetime imaging for intracellular pH sensing in living tissues
N2  - pH sensing in living cells represents one of the most prominent topics in biochemistry and physiology. In this study we performed one-photon and two-photon time-domain fluorescence lifetime imaging with a laser-scanning microscope using the time-correlated single-photon counting technique for imaging intracellular pH levels. The suitability of different commercial fluorescence dyes for lifetime-based pH sensing is discussed on the basis of in vitro as well of in situ measurements. Although the tested dyes are suitable for intensity-based ratiometric measurements, for lifetime- based techniques in the time-domain so far only BCECF seems to meet the requirements of reliable intracellular pH recordings in living cells.
Y1  - 2008
U6  - https://doi.org/10.1007/s00216-008-2147-0
ER  -