Fig. 4: Mechanism of photooxidation and its morphology dependence.
From: Nanomorphology dependence of the environmental stability of organic solar cells
a TA spectra and b TA decay of pristine PTB7 and 80:20% and 50:50% PTB7:PCBM blends. TA spectra were measured at 0.5, 1, 2, and 5 μs after laser excitation from top to bottom. TA decay was probed at 1160 nm in a nitrogen atmosphere, and the corresponding dynamics were well fitted with either a monoexponential decay function (dashed line) or the sum of an exponential decay and a power law decay function (solid lines). c Yield of PTB7 triplet excitons as a function of the weight ratios of PCBM. d Schematic illustration of the photooxidation mechanism of PTB7:PCBM blends.
