Well-controlled thieno[3,4-c]pyrrole-4,6-(5H)-dione based conjugated polymers for high performance organic photovoltaic cells with the power conversion efficiency exceeding 9%

Abstract

We have synthesized a series of conjugated D-p-A copolymers, PT-ttTPD and PBT-ttTPD, based on a (5-hexyltridecyl)-4Hthieno[3,4-c]pyrrole-4,6(5H)-dione (ttTPD) acceptor unit in order to develop better photovoltaic polymers based on the TPD moiety: an e-branched alkyl side chain on the TPD unit was coupled with 6-alkyl-thieno[3,2-b]thiophene (tt) p-bridge molecules. The Stille polymerization of the brominated ttTPD and stannylated simple thiophene (T) finally gave a promising PT-ttTPD polymer showing well-ordered inter-chain orientation in the BHJ active layer. PT-ttTPD-based OPVs exhibited a highest power conversion efficiency (PCE) of 9.21% (V OC = 0.86 V, J SC = 15.30 mA cm À2 , FF = 70%).

A New Polythiophene Derivative for High Efficiency Polymer Solar Cells with PCE over 9%

“…[25] As a result, the corresponding PSCs showed an enhanced PCE of 7.2% with increased V oc of 0.91 V. In addition, to construct the D-A type PT derivatives by introducing the thiophene-based acceptor units has been proved to be an effective way to modulate the energy levels of PT derivatives. [24,34] The PT derivative PBT1 with the thiophene fused benzodithiophene-4,8-dione (BDD) acceptor unit was reported and showed a lower HOMO level (−5.13 eV), and an improved PCE of 6.88% was achieved with V oc of 0.83 V in the PBT1-based PSCs. [24] More interestingly, this method can simultaneously reduce the bandgap of PT derivatives, resulting in the broadening of absorption, which benefits for increasing J sc and PCE.…”

Photovoltaic properties of a new quinoxaline-based copolymer with Thieno[3,2-b]thiophene side chain for organic photovoltaic cell applications

“…Interestingly, the J SC values measured for the devices fabricated using the two polymers were different at 5.67 and 8.50 mA cm À2 for PBDT-TDTQx and PBDT-TTDTQx, respectively. The difference in the J SC values of the two devices mainly originated from the molecular ordering, charge carrier mobility, and absorption of the active layers [30].…”

“…2D-GIXD measurements were performed to gain insight into the characteristics of the polymer nano structures in the blend films such as crystallite orientation, crystal coherence length, and intermolecular distance [30,31]. Fig.…”

Understanding the Role of Phenanthroline as Interlayer in Bulk Heterojunction Organic Photovoltaic Cells

“…Organic photovoltaic cells (OPVs) based on bulk heterojunctions (BHJ) of conjugated polymers and fullerenes have shown a significant increase of power conversion efficiency (PCE), climbing up to over 8–9 % for single junction devices and over 11.5 % for tandem structures . The intrinsic merits of this technology, that uses solution processing to fabricate large‐area, light‐weight, mechanical flexible, low cost solar panels have been a strong driving force to bring it to the market.…”

“…Yet, to win over competing and well‐established technologies, additional efforts are required not only to further increase PCE of solar modules but also to improve devices stability. Most crucial efforts to improve cells performance have included materials development (specially of highly absorbing polymers), optimization of blend morphology, interface modifications, and exploration of non‐conventional device architectures as inverted structures . In particular, the insertion of interlayers between the photoactive layer and the electrodes can have multifold beneficial effects and various materials have been applied, such as alkali metal salts (e. g. LiF), metal‐oxides, organic materials, and combinations thereof, to exploit optical and electronic materials properties.…”