Evaluation of the photocurrent value for poly(2,5-dicyano- p -phenylene-vinylene)-co-(p-phenylene-vinylene) (DCN-PPV/PPV)

Abstract

A method to obtain poly(2,5-dicyano-p-phenylenevinylene)-co-(p-phenylene-vinylene) (DCN-PPV/PPV) block copolymer was developed. The structural characteristics of the copolymer and its capability to generate a photocurrent were evaluated. IR spectra indicate the complete conversion of precursor copolymer into DCN-PPV/PPV at 250°C under lowpressure conditions. The DCN-PPV/PPV polymer optical band gap was determined based on the observed UV-Vis spectral data by using Tauc's equation. The two linear regions in the Tauc curve (E g = 2.63 eVand 2.02) revealed the formation of a block copolymer. Thermal analysis showed that DCN-PPV/PPV has a higher stability than PPV and starts to degrade at 317°C in air. The electronic parameters of DCN-PPV/PPV (IP = 5.25 eV, EA = 3.30 eV, and E g = 1.95 eV) indicate that the cyano groups reduce the LUMO energy level without affecting the HOMO energy by much. DCN-PPV/PPV photoactivity measurements show higher photocurrent values compared to those for PPV.

Short-Range π–π Stacking Assembly on P25 TiO2 Nanoparticles for Enhanced Visible-Light Photocatalysis

“…The inverted photocurrent may be attributed to a strong reduction in the formation of photogenerated electrons and electron flow to the Pt electrode. 60 Upon the excitation of pure PTCDI selfassembly, the photocurrent density stayed at ∼0.2 μA/cm 2 . The initial photocurrent of the 8% hybrid reached 1.7 μA/cm 2 and then remained at a stationary value of ∼1.0 μA/cm 2 , 5.0 times higher than that of pure PTCDI self-assembly, because of the reduced charge recombination.…”

“…During the light-on period, 2% PTCDI/P25 displayed a stationary positive photocurrent due to ultrafast interfacial ET, while the other hybrids first showed a sharp rise followed by decay to a near-stationary negative photocurrent which represented the dynamic equilibrium between charge separation and recombination. The inverted photocurrent may be attributed to a strong reduction in the formation of photogenerated electrons and electron flow to the Pt electrode . Upon the excitation of pure PTCDI self-assembly, the photocurrent density stayed at ∼0.2 μA/cm 2 .…”

“…The initial photocurrent of the 8% hybrid reached 1.7 μA/cm 2 and then remained at a stationary value of ∼1.0 μA/cm 2 , 5.0 times higher than that of pure PTCDI self-assembly, because of the reduced charge recombination. The spike peak at 30 s may result from charge recombination caused by long-range electron transmission . To enhance the conductivity between the hybrid and ITO glass, poly­(vinylidene fluoride) (PVDF) and carbon black were mixed with the hybrid, and the plots are shown in Figure S11a in the Supporting Information.…”

“…The spike peak at 30 s may result from charge recombination caused by long-range electron transmission. 60 To enhance the conductivity between the hybrid and ITO glass, poly(vinylidene fluoride) (PVDF) and carbon black were mixed with the hybrid, and the plots are shown in Figure S11a in the Supporting Information. The total trend was the same as the result above.…”

Stability and Performance Enhancement of an Oligo (phenylene vinylene) Photocatalyst via Surface Grafting onto TiO2 for Visible‐Light Indigo Carmine Degradation

“…Such difficulties arise as a significant limitation, narrowing down the options for these metal‐free systems from being widely explored for light‐driven catalysis [12–16] . Consequently, some synthetic strategies have sought to improve the photostability of phenylene vinylene (PV) systems, highlighting those that consist of the insertion of electrons withdrawing groups (EWG) such as −CN, −F, −NO 2 , and −CF 3 around the conjugated scaffold and the sp 3 ‐bridged rigidification of the PV backbone, [17–21] as techniques to reduce the reactive oxygen species (ROS) reaction rate. Furthermore, to protect the organic structure and avoid any inactivation, a great effort has also been made to heterogenize various metal‐free conjugated organic systems using different inorganic supports such as carbon nanotubes, silicates, polymers, and molecular sieves [22–25] .…”