PM6 (PBDB-T-2F) is a donor-acceptor (D-A) copolymer composed of 4,8-bis(5-(2-ethylhexyl)-4-fluorothien-2-yl)benzo[1,2-b:4,5-b']dithienes (BDT) and 1, 3-bis(thien-2-yl)-5,7-bis(2-ethylhexyl)benzo[1,2-c:4,5-c']dithiophene-4,8-dione (BDD) units. It is also a fluorinated derivative of PBDB-T and is frequently employed as a material in organic photovoltaics (OPVs). PM6 possesses a large bandgap of 1.80 eV with a strong absorption spectrum in the range from 500 to 700 nm. Y6 contains an
electron-deficient central core based on dithienothiophen[3,2-b]
pyrrolobenzothiadiazole with 2-(5,6-Difluoro-3-oxo-2,3-dihydro
1H-inden-1-ylidene)malononitrile units as flank units. The strong and well complementary light absorption spectra of PM6 and Y6 is the prerequisite for obtaining high
photocurrent responses in OPV devices. By combining PM6 with the non-fullerene acceptor Y6 in an in-plane heterojunction structure (PM6:Y6 BHJ), photovoltaic conversion efficiencies (PCEs) as high as 20% have been achieved.
[1] RUNNAN YU; Zhan’ao T; Guangzheng Wu. Realization of high performance for PM6:Y6 based organic photovoltaic cells[J]. Energy Chemistry, 2021, 61: Pages 29-46. DOI:
10.1016/j.jechem.2021.01.027.
High-Efficiency Organic Solar Cells (OPVs)
Polymeric donor material
LUMO=3.6 eV
HOMO=5.5 eV
OPV Device Performance:
PBDB-T-2F: ITIC-F (1:1 w/w)
Voc= 0.84V
Jsc= 22.2 mA/cm2
FF= 0.725
PCE=13.5%
PBDB-T-2F (or PM6) is a wide bandgap polymer donor (n-type semiconductor) containing fluorinated thienyl benzodithiophene (BDT-2F) used in high performance polymer solar cells (PSCs). PBDB-T-2F possesses high crystallinity and strong π-π stacking alignment, which are favourable to charge carrier transport and hence suppress recombination in devices. PBDBT-2F based PSCs were reported to have thickness and area insensitive performance and is a promising candidate for large-scale roll-to-roll manufacturing of high-efficiency polymer solar cells.
For example, recently, new study have shown PBDB-T-2F:IT-4F(Sigma Aldrich Cat. No. 901423) based PSCs yielded an impressive PCE of 13.5% due to the synergistic effect of fluorination on both donor and acceptor, which is among the highest values recorded in the literatures for PSCs to date [1]. The PBDB-T-2F:IT-4F baed PSCs also showed good storage, thermal and illumination stabilities with respect to the efficiency. High efficiency of >11% was maintained for a wide range of film area and thickness. When paired with selenopheno[3,2-b]thiophene-based narrow-bandgap non-fullerene acceptor, an impressive efficiency of 13.3 % was obtained with thickness-insensitive feature.
It has also been previously reported, PBDB-T-2F when paired with narrow band-gap small molecule acceptor 2,2′-((2Z,2′Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IDIC), the as-cast film (without extra treatments) showed an outstanding power conversion efficiency (PCE) of 11.9%, a record value for as-cast polymer solar cells. Moreover, the performance of PBDB-T-2F:IDIC based devices is insensitive to the active layer thickness (95-255 nm) and device area (0.20-0.81 cm2), and thus is a promising candidate for future roll-to-roll mass manufacturing and practical application of highly efficient PSCs.
It has also been reported, PBDB-T-2F possesses a strong absorption in the short wavelength region of 300-685 nm with a large bandgap of 1.80 eV, which is complementary to that of ITIC (1.55 eV) and facilitates achieving high short-circuit current (Jsc) in PSCs. Moreover, PBDB-T-2F shows a deep HOMO level of 5.50 eV, a strong crystallinity and a dominant face on packing, which helps to achieve a high open-circuit voltage (Voc) and fill factor (FF) in PSCs.
