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Here, we studied the potential of 2,3‐didodecyl‐6‐fluoroquinoxaline–based polymer as an electron‐donor in binary and ternary organic solar cell (OSC) applications. A new wide bandgap polymeric donor, namely poly(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene‐alt‐2,3‐didodecyl‐6‐fluoro‐5,8‐di(thiophen‐2‐yl)quinoxaline) (P(BDTT‐TfQT)), is prepared. Polymer P(BDTT‐TfQT) showed intense absorption between 300 and 650 nm with an optical band gap of 1.83 eV. The determined highest occupied and lowest unoccupied molecular orbitals (highest occupied molecular orbital/lowest unoccupied molecular orbital = −5.28 eV/−3.45 eV) for P(BDTT‐TfQT) are found to be suitable to utilize as an electron donor along with widely used fullerene and non‐fullerene acceptors. The OSCs prepared by using P(BDTT‐TfQT):fullerene blend gave a maximum power conversion efficiency (PCE) of 4.64%, and the PCE further increased to 6.77% by using a non‐fullerene acceptor instead of fullerene. Overall, the improved light absorption results in higher photo‐current and PCE for P(BDTT‐TfQT):non‐fullerene blend compared to that of P(BDTT‐TfQT):fullerene blend. In contrast, the inclusion of 10 vol% of P(BDTT‐TfQT) as a third component in a high energy converting polymer: non‐fullerene blend is found to lower the performance from 16.03% to 14.50% for the resulting ternary OSCs. [ABSTRACT FROM AUTHOR]

We synthesized two new alternating polymers, namely P(Tt‐FQx) and P(Tt‐DFQx), incorporating electron rich tri‐thiophene and electron deficient 6‐fluoroquinoxaline or 6,7‐difluoroquinoxaline derivatives. Both polymers P(Tt‐FQx) and P(Tt‐DFQx) exhibited high thermal stabilities and the estimated 5% weight loss temperatures are 425 and 460 °C, respectively. Polymers P(Tt‐FQx) and P(Tt‐DFQx) displayed intense absorption band between 450 and 700 nm with an optical band gap (Eg) of 1.78 and 1.80 eV, respectively. The determined highest occupied/lowest unoccupied molecular orbital's (HOMO/LUMO) of P(Tt‐DFQx) (−5.48 eV/−3.68 eV) are slightly deeper than those of P(Tt‐FQx) (−5.32 eV/−3.54 eV). The polymer solar cells fabricated with a device structure of ITO/PEDOT:PSS/P(Tt‐FQx) or P(Tt‐DFQx):PC70BM (1:1.5 wt %) + 3 vol % DIO/Al offered a maximum power conversion efficiency (PCE) of 3.65% with an open‐circuit voltage (Voc) of 0.59 V, a short‐circuit current (Jsc) of 10.65 mA/cm2 and fill factor (FF) of 59% for P(Tt‐FQx)‐based device and a PCE of 4.36% with an Voc of 0.69 V, a Jsc of 9.92 mA/cm2, and FF of 63% for P(Tt‐DFQx)‐based device. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 545–552 Two new polymeric donor materials, namely P(Tt‐FQx) and P(Tt‐DFQx), comprising tri‐thiophene and mono‐ or difluoro‐substituted quinoxaline derivatives are synthesized for polymer solar cell applications. Mono‐fluoro‐substituted quinoxaline‐based polymer P(Tt‐FQx) showed more improved absorption than that of di‐fluoro‐substituted quinoxaline‐based polymer P(Tt‐DFQx), while P(Tt‐DFQx) exhibited deeper HOMO level than that of P(Tt‐FQx). Conversely, P(Tt‐FQx) offered higher photocurrent while P(Tt‐DFQx) gave higher open‐circuit voltage. Therefore, both polymers provided comparable photovoltaic performance of 3.65% and 4.36%, respectively, for the polymer solar cell devices made by using P(Tt‐FQx) or P(Tt‐DFQx):PC70BM blends. [ABSTRACT FROM AUTHOR]

In this study, two new pyrrolo[3,4-c]pyrrole-1,3-dione (PPD)-based polymers (P3 and P4) incorporating a 2-octyldodecyl (branched alkyl) group on the pyrrole nitrogen of the PPD unit were prepared. Their properties were briefly compared to those of the structurally quite similar PPD-based polymers (P1 and P2) with an n-octyl (linear alkyl) group on the PPD unit, in order to understand the importance of the pyrrole N-alkyl group. The calculated optical band gaps (Eg) and highest occupied molecular orbital energy levels of P3 and P4 were found to be around ∼0.1 eV higher and deeper, respectively, compared to those of the respective linear alkylated polymers P1 and P2. The maximum power conversion efficiency (PCE) obtained for the polymer solar cells made by using P3 or P4:PC70BM blends without any additive was around ∼2%, which was quite similar to that of the PSCs made using P1 or P2:PC70BM blends. However, P3 and P4 exhibited a notably lower PCE than that of P1 and P2, respectively, when the polymer solar cells were created with an additive. This study confirmed that the alkyl substituent on the pyrrole nitrogen of the PPD unit significantly affects the properties of the resulting polymer. [ABSTRACT FROM AUTHOR]

Two new tercopolymers (RP1 and RP2) containing electron-donating benzodithiophene, weak electron-accepting pyrrolo[3,4-c]pyrrole-1,3-dione derivative and strong electron-accepting 5,6-difluorobenzothiadiazole derivative were prepared. The opto-electrical studies showed that RP1 and RP2 displayed identical optical band gaps ( E ~ 1.72 eV) and highest occupied/lowest unoccupied molecular orbital energy levels (HOMO/LUMO ~ −5.32 eV/−3.60 eV). The polymer solar cells prepared with the configuration of ITO/PEDOT:PSS/RP1:PCBM (1:1.5 wt%) + 3 vol% DIO/Al and ITO/PEDOT:PSS/RP2:PCBM (1:1.5 wt%) + 3 vol% DIO/Al exhibited a maximum power conversion efficiency (PCE) of 5.16% ( V ~ 0.76 V, J ~ 10.93 mA/cm, and FF ~ 0.62) and a PCE of 3.56% ( V ~ 0.67 V, J ~ 9.67 mA/cm, and FF ~ 0.55), respectively. [ABSTRACT FROM AUTHOR]

A pyrrole-based, imide-functionalized, electron-deficient monomer unit, 4,6-dibromo-2,5-dioctylpyrrolo [3,4-c]pyrrole-1,3(2H,5H)-dione (DPPD), was copolymerized with electron-rich 2,6-bis(trimethyltin)-4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b']dithiophene to afford the polymer P(BDT-DPPD). The weight-averaged molecular weight (Mw) of P(BDT-DPPD) was 6.41 x 10³ g/mol with a polydispersity index (PDI) of 1.32. P(BDT-DPPD) displayed a broad absorption band from 300 to 600 nm with onset absorption at 596 nm in the film state. The calculated optical bandgap of P(BDT-DPPD) was 2.08 eV, and the estimated highest occupied molecular orbital energy level of P(BDT-DPPD) was -5.48 eV. The polymer solar cell (PSC) fabricated in the ITO/PEDOT:PSS/P(BDT-DPPD)/PC70BM (1:2wt%)/Al configuration was found to give a maximum power conversion efficiency (PCE) of 1.46% with an open-circuit voltage (Voc) of 0.79 V, a current density (Jsc) of 4.59 mA/cm², and a fill factor (FF) of 40%. [ABSTRACT FROM AUTHOR]

In an attempt to find a suitable visible light absorber, a TDQD[( E )-3-(5-(4-(5-(4-(bis(4-(hexyloxy)phenyl)amino)phenyl)thiophen-2-yl)-6,7-diethyl-[1,2,5]thiadiazolo[3,4-g]quinoxalin-9-yl)thiophen-2-yl)-2-cyanoacrylic acid] dye is synthesized and introduced onto the surfaces of commercialized TiO 2 (P-25) particles as a photosensitizer to improve their photo-absorption in the visible range. The photocatalytic performance of the TDQD-photosensitized - TiO 2 is superior to that of the non-photosensitized TiO 2 nanomaterial: the photoreduction of CO 2 to CH 4 is remarkably improved on the former with the production of 1290 μmol g cat −1 L −1 of CH 4 after 8 h of reaction. These results are attributed to the effective visible light absorption and charge separation, and the inhibited recombination of the photogenerated electron–hole pairs on the TDQD-photosensitized-TiO 2 . Finally, the prepared TDQD and TDQD-photosensitized - TiO 2 powders were characterized through cyclic voltammetry (CV), ultraviolet-visible (UV–vis) and FT-IR spectroscopies and photocurrent density analysis. [ABSTRACT FROM AUTHOR]