Luminosyn™ DPP-DTT

Luminosyn™ DPP-DTT (also referred to as PDPP2T-TT-OD) is now available.

OFET and Sensing Applications

The exceptional high mobility of this polymer of up to 10 cm2/Vs [2] via solution-processed techniques, combined with its intrinsic air stability (even during annealing) has made PDPP2T-TT-OD of significant interest for OFET and sensing purposes.

While the highest mobilities require exceptional molecular weights of around 500 kD (and with commensurate solubility issues), high mobilities in the region of 1-3 cm2/Vs can still be achieved with good solution-processing at around 250 kD. As such, we have made a range of molecular weights available to allow for different processing techniques.

In our own tests, we have found that by using simple spin-coating onto an OTS-treated silicon substrate (using our prefabricated test chips), high mobilities comparable to the literature can be achieved  (1-3 cm2/Vs). Further improvements may also be possible with more advanced strain-inducing deposition techniques.

   
  

Photovoltaic Applications

Although shown as a promising hole-mobility polymer for OFETs, when used as the donor material in a bulk heterojunction photovoltaic (with PC70BM as the acceptor), initial efficiencies of 1.6% were achieved for DPP-DTT [3]. The low device metrics were attributed to poor film morphology. However, a higher efficiency of 6.9% was achieved by using thicker film (220 nm) [4].

PDPP2T-TT-OD has also recently been used successfully as an active-layer dopant material in PTB7-based devices [5]. An improvement in device performance was observed, with average efficiencies increasing from 7.6% to 8.3% when the dopant concentration of DPP-DTT was 1 wt%. The use of DPP-DTT as a high-mobility hole-interface layer for perovskite hybrid devices has also been investigated [6].

Synthetic route

DPP-DTT synthesis: DPP-DTT was synthesised by following the procedures described in [2] and [3] (please refer to the following references):

With 2-thiophenecarbonitrile and dimethyl succinate as starting materials in t-amyl alcohol, it gave 3,6-Dithiophen-2-yl-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione. Alkylation of 3,6-Dithiophen-2-yl-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione with 2-octyldodecylbromide in dimethylformamide afforded 3,6-bis(thiophen-2-yl)-2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione. Further bromination gave 3,6-bis(5-bromothiophen-2-yl)-2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (M1).

Further reaction of M1 with 2,5-bis(trimethylstannyl)thieno[3,2-b]thiophene (M2) under Stille coupling conditions gave the target polymer DPP-DTT, which was further purified via Soxhlet extraction with methanol, hexane and then chloroform.

General Information