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Significance of Average Domain Purity and Mixed Domains on the Photovoltaic Performance of High‐Efficiency Solution‐Processed Small‐Molecule BHJ Solar Cells
Author(s) -
Mukherjee Subhrangsu,
Proctor Christopher M.,
Bazan Guillermo C.,
Nguyen ThucQuyen,
Ade Harald
Publication year - 2015
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.201500877
Subject(s) - materials science , photovoltaic system , recombination , molecule , charge (physics) , phase (matter) , organic solar cell , chemical physics , small molecule , energy conversion efficiency , analytical chemistry (journal) , optoelectronics , polymer , organic chemistry , chemistry , physics , ecology , biochemistry , biology , composite material , gene , quantum mechanics
Whereas the role of molecularly mixed domains in organic photovoltaic devices for charge generation is extensively discussed in the literature, the impact on charge recombination and thus fill factor is largely unexplored. Here, a combination of soft X‐ray techniques enables the quantification of phases at multiple length scales to reveal their role regarding charge recombination in a highly efficient solution processed small molecule system 7,7′‐(4,4‐bis(2‐ethylhexyl)‐4H‐silolo[3,2‐b:4,5‐b′]dithiophene‐2,6‐diyl)bis(6‐fluoro‐4‐(5′‐hexyl‐[2,2′‐bithiophen]‐5‐yl)benzo[c][1,2,5]thiadiazole) (p‐DTS(FBTTh 2 ) 2 ) . A quantitative (linear) relationship between the average composition variations and the device fill‐factor is observed. The results establish the complex interrelationship between average phase purity, domain size, and structural order and highlight the requirement of achieving sufficient phase purities to diminish bimolecular and geminate recombination in solution processed small molecule solar cells.