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Influence of Thermal Annealing on PCDTBT:PCBM Composition Profiles
Author(s) -
Synooka Olesia,
Eberhardt KaiRudi,
Singh Chetan Raj,
Hermann Felix,
Ecke Gernot,
Ecker Bernhard,
von Hauff Elizabeth,
Gobsch Gerhard,
Hoppe Harald
Publication year - 2014
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201300981
Subject(s) - materials science , annealing (glass) , dielectric spectroscopy , wetting , wetting layer , auger electron spectroscopy , pedot:pss , chemical engineering , energy conversion efficiency , analytical chemistry (journal) , thermal stability , spectroscopy , quantum efficiency , polymer solar cell , optoelectronics , electrode , polymer , composite material , organic chemistry , chemistry , physics , electrochemistry , quantum mechanics , nuclear physics , engineering
A variety of measurement techniques including photothermal deflection spectroscopy (PDS), auger electron spectroscopy (AES), (sub–bandgap) external quantum efficiency (EQE), and impedance spectroscopy are applied to poly[N‐900‐hepta‐decanyl‐2,7‐carbazole‐alt‐5,5‐(40,70‐di‐2‐thienyl‐20,10,30‐benzothiadiazole (PCDTBT)/[6,6]‐phenyl C 71 butyric acid methyl ester (PC 71 BM) films and devices to probe the stability under thermal annealing. Upon annealing, solar cell performance is drastically decreased for temperatures higher than 140 °C. Detailed investigation indicate changes in polymer:fullerene interactions resulting in the formation of a polymer wetting layer upon annealing at temperatures higher than 140 °C. Upon device completion this wetting layer is located close to the metal electrode and therefore leads to an increase in recombination and a decrease in charge carrier extraction, providing an explanation for the reduced fill factor (FF) and power conversion efficiency (PCE).