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Charge Creation and Recombination in Multi‐Length Scale Polymer:Fullerene BHJ Solar Cell Morphologies
Author(s) -
Mukherjee Subhrangsu,
Jiao Xuechen,
Ade Harald
Publication year - 2016
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.201600699
Subject(s) - fullerene , materials science , length scale , volume fraction , polymer , polymer solar cell , solar cell , organic solar cell , chemical physics , charge (physics) , volume (thermodynamics) , recombination , photovoltaic system , heterojunction , nanotechnology , optoelectronics , thermodynamics , chemistry , physics , composite material , organic chemistry , ecology , biochemistry , quantum mechanics , biology , gene
While the extremes in organic photovoltaic bulk heterojunction morphology (finely mixed or large pure domains) are easily understood and known to be unfavorable, efficient devices often exhibit a complex multi‐length scale, multi‐phase morphology. The impact of such multiple length scales and their respective purities and volume fractions on device performance remains unclear. Here, the average spatial composition variations, i.e., volume‐average purities, are quantified at multiple size scales to elucidate their effect on charge creation and recombination in a complex, multi‐length scale polymer:fullerene system (PBDTTPD:PC 71 BM). The apparent domain size as observed in TEM is not a causative parameter. Instead, a linear relationship is found between average purity at length scales <50 nm and device fill‐factor. Our findings show that a high volume fraction of pure phases at the smallest length scales is required in multi‐length scale systems to aid charge creation and diminish recombination in polymer:fullerene solar cells.