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Real-time Photoluminescence Studies of Thin Film Formation in Organic Solar Cells



Sebastian Engmann, Felicia A. Bokel, Hyun W. Ro, Dean M. DeLongchamp, Lee J. Richter


We present a method to study the structural evolution of organic bulk-heterojunctions via real-time, in-situ, steady state photoluminescence (PL). In-situ PL, in combination with real-time transmission and reflection measurements, allowed us to quantitatively describe the progression of intimate mixing during blade coating of two OPV systems: the common model system poly(3-hexylthiophene-2,5-diyl) / phenyl-C61-butyric-acid-methyl ester ( P3HT / [60]PCBM), and the higher power conversion efficiency system 7,7’-(4,4bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b’]dithiophene-2,6-diyl)bis(6-fluoro-5-(5’-hexyl-[2,2’-bithiophen]-5-yl)benzo[c][1,2,5]thiadiazaole), p-DTS(FBTTh2)2 / [70]PCBM. Evaluating the time dependence of the PL-intensity during drying using a 3D-random walk diffusion model allowed for the quantitative determination of the ratio of characteristic domain size to exciton diffusion length during solidification in the presence of processing additives 1-chloronaphtalene (CN), 1,8-octanedithiol (ODT) and 1,8-diiodooctane (DIO). In both cases the obtained results were in good agreement with the typically observed fibril widths and grain sizes, for P3HT and p-DTS(FBTTh2)2 respectively.
Advanced Energy Materials


Photoluminescence, UV-Vis, In-situ, Bulk heterojunction, Polymer, Small-molecule, Fullerene


Engmann, S. , Bokel, F. , Ro, H. , DeLongchamp, D. and Richter, L. (2016), Real-time Photoluminescence Studies of Thin Film Formation in Organic Solar Cells, Advanced Energy Materials, [online], (Accessed April 23, 2024)
Created February 29, 2016, Updated November 10, 2018