Photovoltaic (PV) utilization of solar energy is one of the least exploited and most promising carbon-neutral methods available today. Over recent years organic solar cells have been perfected at the laboratory level with a record PCE of 10.6% 1 for polymer solution processed devices and a large area module PCE of 5.5%2 which may challenge a-Si PV technology. In recent years, conjugated polymers have attracted more and more attention due to their growing efficiencies in plastic solar cells.3 Donor low band gap copolymer, which combine carbazole with electronwithdrawing dithienylbenzothiadiazole4 or benzothiadiazole (P1) units has been reported. In order to allow better efficiencies we have been designed and synthetized new electron-withdrawing comonomers, containing bis-imine aromatic ligands (1,2-diazine) to exploit metal coordination for lowering the LUMO level and increase absorption in the visible region. Here we report the synthesis of 5,8-dibromophthalazine (M2) and 5,7-dibromothieno[3,4-d]pyridazine (M3). These two monomers have then been polymerized with the boronic derivative of carbazole comonomer by a Suzuki-Miyaura coupling , obtaining the corresponding P2 and P3 copolymers in good yields. In order to further lower the diazine based polymer LUMO level, P2 and P3 have therefore been used as ligands in neutral dinuclear rhenium(I) complexes of formula [Re2(CO)6(µ-X)(µ-Y)(µ-diazine)] 5 (where X and Y are bridging anionic ligands) thus obtaining the corresponding metallo-copolymers ReP2 and ReP3. Metal coordination have also enhanced photo-induced charge separation and thermal stability. Spectroscopic (NMR, IR, UV-Vis, Photoluminescence) and electrochemical (cyclic voltammetry) characterizations of the new monomers M2 and M3, and of the materials (P2, P3, ReP2 and ReP3) in solution and as film have been performed and the data have been compared with those obtained for the "reference" polymer P1. NMR and MALDI TOF characterizations reveal a different enchainment between comonomers in polymeric backbone depending on the nature of electronwithdrawing unit and affecting electronic and thermal properties. 1. Dou et al., Nature Photonics 2012, 6, 181 2. IMEC and Solvay, 2012 3. (a) H. Chen, J. Hou, S. Zhang, Y. Liang, G. Yang, Y. Yang, L. Yu, Y. Wu, G. Li, Nat. Photonics 2009, 3, 649. (b) N. Blouin, A. Michaud, M. Leclerc, Adv. Mater. 2007, 19, 2295 4. N. Blouin, A. Michaud, D. Gendron, S. Wakim, E. Blair, R. N.Plesu, M. Bellete^te, G. Durocher, Y. Tao, M. Leclerc, J. Am. Chem.Soc. 2008, 130, 732. 5. M. Panigati et al. Coord. Chem. Rev. 2012, 256, 1621.
New carbazole based copolymers and Re metal complexes for optoelectronic (or photovoltaic) applications
STEFANIA ZAPPIA;SALVATORE BATTIATO;FILIPPO SAMPERI;
2016
Abstract
Photovoltaic (PV) utilization of solar energy is one of the least exploited and most promising carbon-neutral methods available today. Over recent years organic solar cells have been perfected at the laboratory level with a record PCE of 10.6% 1 for polymer solution processed devices and a large area module PCE of 5.5%2 which may challenge a-Si PV technology. In recent years, conjugated polymers have attracted more and more attention due to their growing efficiencies in plastic solar cells.3 Donor low band gap copolymer, which combine carbazole with electronwithdrawing dithienylbenzothiadiazole4 or benzothiadiazole (P1) units has been reported. In order to allow better efficiencies we have been designed and synthetized new electron-withdrawing comonomers, containing bis-imine aromatic ligands (1,2-diazine) to exploit metal coordination for lowering the LUMO level and increase absorption in the visible region. Here we report the synthesis of 5,8-dibromophthalazine (M2) and 5,7-dibromothieno[3,4-d]pyridazine (M3). These two monomers have then been polymerized with the boronic derivative of carbazole comonomer by a Suzuki-Miyaura coupling , obtaining the corresponding P2 and P3 copolymers in good yields. In order to further lower the diazine based polymer LUMO level, P2 and P3 have therefore been used as ligands in neutral dinuclear rhenium(I) complexes of formula [Re2(CO)6(µ-X)(µ-Y)(µ-diazine)] 5 (where X and Y are bridging anionic ligands) thus obtaining the corresponding metallo-copolymers ReP2 and ReP3. Metal coordination have also enhanced photo-induced charge separation and thermal stability. Spectroscopic (NMR, IR, UV-Vis, Photoluminescence) and electrochemical (cyclic voltammetry) characterizations of the new monomers M2 and M3, and of the materials (P2, P3, ReP2 and ReP3) in solution and as film have been performed and the data have been compared with those obtained for the "reference" polymer P1. NMR and MALDI TOF characterizations reveal a different enchainment between comonomers in polymeric backbone depending on the nature of electronwithdrawing unit and affecting electronic and thermal properties. 1. Dou et al., Nature Photonics 2012, 6, 181 2. IMEC and Solvay, 2012 3. (a) H. Chen, J. Hou, S. Zhang, Y. Liang, G. Yang, Y. Yang, L. Yu, Y. Wu, G. Li, Nat. Photonics 2009, 3, 649. (b) N. Blouin, A. Michaud, M. Leclerc, Adv. Mater. 2007, 19, 2295 4. N. Blouin, A. Michaud, D. Gendron, S. Wakim, E. Blair, R. N.Plesu, M. Bellete^te, G. Durocher, Y. Tao, M. Leclerc, J. Am. Chem.Soc. 2008, 130, 732. 5. M. Panigati et al. Coord. Chem. Rev. 2012, 256, 1621.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
