In this study, we found that the work functions (Φ(w)) of solution-processable, functional graphene/carbon nanotube-based transparent conductors were readily manipulated, varying between 5.1 and 3.4 eV, depending on the nature of the doping alkali carbonate salt. We used the graphene-based electrodes possessing lower values of Φ(w) as cathodes in inverted-architecture polymer photovoltaic devices to effectively collect electrons, giving rise to an optimal power conversion efficiency of 1.27%.

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Six novel conjugated copolymers (P1-P6) containing coplanar cyclopentadithiophene (CPDT) units (incorporated with bithiazole/thienyl-based monomers) were synthesized and developed for the applications of polymer solar cells (PSCs). Copolymers P1-P6 covered broad absorption ranges from UV to near-infrared (400-800 nm) with narrow optical band gaps of 1.70-1.94 eV, which are compatible with the maximum solar photon reflux. Partially reversible p-and n-doping processes of P1-P6 in electrochemical experiments were observed. Compared with those previously reported CPDT-based narrow band gap polymers, the proper molecular design for HOMO/LUMO levels of P1-P6 induced relatively high photovoltaic open-circuit voltages in the PSC devices. Powder X-ray diffraction (XRD) analyses suggested that these copolymers formed highly selfassembled π-π stackings. Under 100 mW/cm 2 of AM 1.5 white-light illumination, bulk heterojunction PSC devices containing an active layer of electron donor copolymers P1-P6 blended with electron acceptor [6,6]phenyl C 61 butyric acid methyl ester (PCBM) in the weight ratio of 1:1 were explored, and the external quantum efficiency (EQE) measurements showed a maximal quantum efficiency of 60%. The PSC device containing P4 in the weight ratio of 1:2 with PCBM gave the best preliminary result with an overall power conversion efficiency (PCE) of 3.04%, an open-circuit voltage of 0.70 V, a short-circuit current of 8.00 mA/cm 2 , and a fill factor of 53.7%.

This paper describes the electrochromic properties of a series of poly(3,4-alkylenedioxythiophene) (PXDOT) derivatives featuring various ring sizes and substitutions. The presence of a bulky group on the monomer resulted in a polymer possessing a more-open morphology, which promoted reversible ionic transfer. We used an electrochemical quartz crystal microbalance and cyclic voltammetry to investigate the properties of these polymers. We found that both cations and anions were involved in the charge compensation process. Furthermore, PXDOT derivatives possessing larger ring sizes and/or longer alkyl substituents exhibited less trapping of ions within the polymer during the redox process. The long-term electrochromic stability of these PXDOTs depended strongly on the number of trapped ions. Although the transmittance attenuation of poly(3,4-ethylenedioxythiophene) (PEDOT) decreased from 53 to 42%, we observed no significant decay for poly (diethyl-3,4-dihydro-2H-thieno[3,4-b]-[1,4]dioxepine) (PProDOT-Et 2 ) after 400 cycles.