Ossila FACT System Guides Us to promising OPV copolymer PFDT2BT-8

Posted on 10 Sep 15:11

Ossila products were used in a recently published paper written by Andrew Pearson et al., which undertook a comparative study on four donor-acceptor benzothiadiazole-based copolymers containing dithienyl or thienothiophene moieties for application in organic photovoltaic devices.

The paper, Impact of dithienyl or thienothiophene units on the optoelectronic and photovoltaic properties of benzo[1,2,5]thiadiazole based donor-acceptor copolymers for organic solar cell devices, studied in detail the structural, electronic and optical properties of copolymers PCDT2BT-8, PFDT2BT-8, PCDTTBT-8 and PFDTTBT-8 in order to define the physical differences between them.

"We find that thienothiophene substitution is an effective method to modify the optical absorption properties of the copolymers. Optical probes show no discernable differences in the photoexcited state quenching efficiency or charge generation yields between each copolymer:PC71BM blend. Probes of film structure using X-ray scattering reveal that whilst the polymer component is largely amorphous in all cases, the degree of PC71BM crystallinity varies between the different polymer-blends studied. In photovoltaic devices, we find that thienothiophene substitution does not result in improved device efficiency. However we find that improved device efficiency (particularly deriving from improved fill-factors) is positively correlated with polymer blends in which there is higher hole mobility and more extensive PC71BM crystallisation."[1]

The paper concluded that the PFDT2BT-8 copolymer demonstrated relatively high efficiencies of 6.2% and therefore holds promise as a suitable semiconductor for single junction OPVs or as a wide band-gap semiconductor for tandem solar cell devices.

Our pre-patterned ITO glass substrates were used during the fabrication of OPVs whilst our silicon oxide substrates were used to produce OFETs. Our FACT System was also used for rapid and accurate characterisation of the devices.

We're currently in the process of developing the new SuperFACT System, which is designed for high throughput, highly accurate experiments and which could reduce R&D testing cycles by up 75%. We hope that SuperFACT will be a valuable testing tool for more comparative studies such as this one where rapid testing of multiple devices is necessary.

A proof of concept prototype unit will be available to view at the upcoming EMRS Conference at Warsaw University of Technology; we'd love to see you there and hear some of your feedback on the system. The conference runs from Monday 16th to Thursday 18th September and you can find Ossila at stall number 4.

Should you have any questions on this paper or the products used please do not hesitate to get in touch.

[1]Impact of dithienyl or thienothiophene units on the optoelectronic and photovoltaic properties of benzo[1,2,5]thiadiazole based donor-acceptor copolymers for organic solar cell devices. Andrew Pearson et al., RSC Advances, 10.1039/C4RA07186G (2014)