摘要： Organic donor–acceptor bulk heterojunction are attracting wide interests for solar cell applications due to solution processability, mechanical ?exibility, and low cost. The photovoltaic performance of such thin ?lm is strongly dependent on vertical phase separation of each component. Although ?lm-depth-dependent light absorption spectra measured by non-in situ methods have been used to investigate the ?lm-depth pro?ling of organic semiconducting thin ?lms, the in situ measurement is still not well-resolved. In this work, we propose an in situ measurement method in combination with a self-developed in situ instrument, which integrates a capacitive coupled plasma generator, a light source, and a spectrometer. This in situ method and instrument are easily accessible and easily equipped in laboratories of the organic electronics, which could be used to conveniently investigate the ?lm-depth-dependent optical and electronic properties.