Author:

Keywords:

Science & Technology, Physical Sciences, Physics, Applied, Physics, SPECTROSCOPY, 02 Physical Sciences, 09 Engineering, 10 Technology, Applied Physics, 40 Engineering, 51 Physical sciences

Abstract:

This letter reports on highly sensitive optical absorption measurements on organic donor-acceptor solar cells, using Fourier-transform photocurrent spectroscopy (FTPS). The spectra cover an unprecedented dynamic range of eight to nine orders of magnitude making it possible to detect defect and disorder related sub-band gap transitions. Direct measurements on fully encapsulated solar cells with an active layer of poly[2-methoxy-5- (3′, 7′ -dimethyl-octyloxy)]-p-phenylene-vinylene:(6,6)-phenyl-C61-butyric-acid (1:4 weight ratio) enabled a study of the intrinsic defect generation due to UV illumination. Solar cell temperature annealing effects in poly(3-hexylthiophene) :PCBM (1:2 weight ratio) cells and the induced morphological changes are related to the changes in the absorption spectrum, as determined with FTPS. © 2006 American Institute of Physics.