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Figure 1

From: Toward Improved Lifetimes of Organic Solar Cells under Thermal Stress: Substrate-Dependent Morphological Stability of PCDTBT:PCBM Films and Devices

Figure 1

Optical microscopy and micron-scale nucleation/growth analysis of PCDTBT:PC60BM blend films on different substrate types.

(a) Optical micrographs of PCDTBT:PC60BM (1:2) thin film mixtures, 85–100 nm thick, annealed at 140 °C for 1 h in N2 environment, supported by three different substrates: SiOx, ZnO and PEDOT:PSS (Scale bar: 25 μm). (b) Temperature dependence of the micron-scale nucleation rate, obtained after 1 h annealing, for SiOx and ZnO substrates. (c) Temperature dependence of the corresponding crystallite growth rate. (PC60BM crystallisation data on SiOx from our previous study [9]). Nucleation and growth rates were estimated by the initial change of crystal number density and length for annealing times up to 60 minutes, at each annealing temperature. Uncertainties were estimated by the maximum deviation obtained from 10 separate measurements, with a scan area of 0.025 mm2.

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