Premium
Photophysics of Molecular‐Weight‐Induced Losses in Indacenodithienothiophene‐Based Solar Cells
Author(s) -
Gasparini Nicola,
Katsouras Athanasios,
Prodromidis Mamantos I.,
Avgeropoulos Apostolos,
Baran Derya,
Salvador Michael,
Fladischer Stefanie,
Spiecker Erdmann,
Chochos Christos L.,
Ameri Tayebeh,
Brabec Christoph J.
Publication year - 2015
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201501062
Subject(s) - materials science , photocurrent , acceptor , charge carrier , polymer , spectroscopy , optoelectronics , organic solar cell , electron mobility , photovoltaic system , polymer solar cell , energy conversion efficiency , analytical chemistry (journal) , chemical physics , photochemistry , organic chemistry , chemistry , condensed matter physics , electrical engineering , physics , quantum mechanics , composite material , engineering
The photovoltaic performance and optoelectronic properties of a donor–acceptor copolymer are reported based on indacenodithienothiophene (IDTT) and 2,3‐bis(3‐(octyloxy)phenyl)quinoxaline moieties (PIDTTQ) as a function of the number‐average molecular weight ( M n ). Current–voltage measurements and photoinduced charge carrier extraction by linear increasing voltage (photo‐CELIV) reveal improved charge generation and charge transport properties in these high band gap systems with increasing M n , while polymers with low molecular weight suffer from diminished charge carrier extraction because of low mobility–lifetime ( μτ ) product. By combining Fourier‐transform photocurrent spectroscopy (FTPS) with electroluminscence spectroscopy, it is demonstrate that increasing M n reduces the nonradiative recombination losses. Solar cells based on PIDTTQ with M n = 58 kD feature a power conversion efficiency of 6.0% and a charge carrier mobility of 2.1 × 10 −4 cm 2 V −1 s −1 when doctor bladed in air, without the need for thermal treatment. This study exhibits the strong correlations between polymer fractionation and its optoelectronics characteristics, which informs the polymer design rules toward highly efficient organic solar cells.