In this study, we have strategically designed and convergently synthesized two novel, symmetrical, and linear A-D-A-type π-conjugated donor molecules (TBDTCNR, TBDTCN), each containing a planar electron-rich 2-octylthiene-5-yl-substituted benzodithiophene (TBDT) unit as the core, flanked by octylthiophene units and end-capped with electron-deficient cyanoacetate (CNR) or dicyanovinyl (CN) units. We thoroughly characterized both of these materials and investigated the effects of the end groups (CNR, CN) on their optical, electrochemical, morphological, and photovoltaic properties. We then fabricated solution-processed bulk heterojunction organic solar cells incorporating TBDTCNR and TBDTCN. Among our tested devices, the one containing TBDTCNR and [6,6]-phenyl-C61-butyric acid methyl ester in a 1:0.40 ratio (w/w) exhibited the highest power conversion efficiency (5.42%) with a short-circuit current density (Jsc) of 9.08 mA cm(-2), an open circuit voltage (Voc) of 0.90 V, and an impressive fill factor (FF) of 0.66 under AM 1.5G irradiation (100 mW cm(-2)). The FFs of these solution-processed small-molecule organic solar cells (SMOSCs) are outstanding when compared with those recently reported for benzodithiophene (BDT)-based SMOSCs, because of the high crystallinity and excellent stacking properties of the TBDT-based compounds.
A series of soluble donor-acceptor conjugated polymers comprising of phenothiazine donor and various benzodiazole acceptors (i.e., benzothiadiazole, benzoselenodiazole, and benzoxadiazole) sandwiched between hexyl-thiophene linkers were designed, synthesized, and used for the fabrication of polymer solar cells (PSC). The effects of the benzodiazole acceptors on the thermal, optical, electrochemical, and photovoltaic properties of these low-bandgap (LBG) polymers were investigated. These LBG polymers possessed large molecular weight (M n ) in the range of 3.85À5.13 Â 10 4 with high thermal decomposition temperatures, which demonstrated broad absorption in the region of 300À750 nm with optical bandgaps of 1.80À1.93 eV. Both the HOMO energy level (À5.38 to À5.47 eV) and LUMO energy level (À3.47 to À3.60 eV) of the LBG polymers were within the desirable range of ideal energy level. Under 100 mW/cm 2 of AM 1.5 white-light illumination, bulk heterojunction PSC devices containing an active layer of electron donor polymers mixed with electron acceptor [6,6]-phenyl-C 61 -butyric acid methyl ester (PC 61 BM) or [6,6]-phenyl-C 71butyric acid methyl ester (PC 71 BM) in different weight ratios were investigated. The best performance of the PSC device was obtained by using polymer PP6DHTBT as an electron donor and PC 71 BM as an acceptor in the weight ratio of 1:4, and a power conversion efficiency value of 1.20%, an open-circuit voltage (V oc ) value of 0.75 V, a short-circuit current (J sc ) value of 4.60 mA/cm 2 , and a fill factor (FF) value of 35.0% were achieved. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: [4823][4824][4825][4826][4827][4828][4829][4830][4831][4832][4833][4834] 2010
In this study we used convergent syntheses to prepare two novel acceptor-donor-acceptor (A-D-A) small molecules (BT4OT, BT6OT), each containing an electron-rich benzotrithiophene (BT) unit as the core, flanked by octylthiophene units, and end-capped with electron-deficient cyanoacetate units. The number of octylthiophene units affected the optical, electrochemical, morphological, and photovoltaic properties of BT4OT and BT6OT. Moreover, BT4OT and BT6OT possess low-energy highest occupied molecular orbitals (HOMOs), providing them with good air stability and their bulk heterojunction (BHJ) photovoltaic devices with high open-circuit voltages (V oc ). A solar cell device containing BT6OT and [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM) in a 1 : 0.75 ratio (w/w) exhibited a power conversion efficiency (PCE) of 3.61% with a short-circuit current density (J sc ) of 7.39 mA cm À2 , a value of V oc of 0.88 V, and a fill factor (FF) of 56.9%. After adding 0.25 vol% of 1-chloronaphthalene (CN) as a processing additive during the formation of the blend film of BT6OT:PC 71 BM (1 : 0.75, w/w), the PCE increased significantly to 5.05% with values of J sc of 9.94 mA cm À2 , V oc of 0.86 V, and FF of 59.1% as a result of suppressed nanophase molecular aggregation.
A series of novel low-bandgap triphenylaminebased conjugated polymers (PCAZCN, PPTZCN, and PDTPCN) consisting of different electron-rich donor main chains (N-alkyl-2,7-carbazole, phenothiazine, and cyclopentadithinopyrol, respectively) as well as cyano-and dicyano-vinyl electronacceptor pendants were synthesized and developed for polymer solar cell applications. The polymers covered broad absorption spectra of 400-800 nm with narrow optical bandgaps ranging 1.66-1.72 eV. The highest occupied molecular orbital and lowest unoccupied molecular orbital levels of the polymers measured by cyclic voltammetry were found in the range of À5.12 to À5.32 V and À3.45 to À3.55 eV, respectively. Under 100 mW/cm 2 of AM 1.5 white-light illumination, bulk heterojunction photovoltaic devices composing of an active layer of electron-donor polymers (PCAZCN, PPTZCN, and PDTPCN) blended with electron-acceptor [6,6]-phenyl-C 61 -butyric acid methyl ester or [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM) in different weight ratios were investigated. The photovoltaic device containing donor PCAZCN and acceptor PC 71 BM in 1:2 weight ratio showed the highest power conversion efficiency of 1.28%, with V oc ¼ 0.81 V, J sc ¼ 4.93 mA/cm 2 , and fill factor ¼ 32.1%. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 5812-5823, 2010
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.