Light Harvesting and Photocurrent Generation in a Conjugated Polymer Nanoparticle–Reduced Graphene Oxide Composite

Abstract

Polymer-graphene nanocomposites are promising candidates for light harvesting applications such as photocatalysis and photovoltaics, where significant charge separation occurs due to photoinduced electron transfer. Much attention has been paid to using reduced graphene oxide (r-GO) as template for anchoring various nanomaterials due to its efficient electron accepting and transport properties. Here, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) nanoparticles are prepared from MEH-PPV polymer and the change in photophysical properties upon formation of polymer nanoparticles (PNPs) from the molecular state are investigated by using steady-state and time-resolved spectroscopy. Nanocomposites are constructed by adding hexadecylamine-functionalized positively charged MEH-PPV PNPs to a solution of negatively charged r-GO. Steady-state and time-resolved spectroscopy are also used to study the electronic interactions between PNPs and r-GO. Ultrafast femtosecond up-conversion and transient absorption spectroscopy unequivocally confirms the electron transfer process from the excited state of MEH-PPV PNPs to r-GO at the interface of the nanocomposite. Analysis reveals that the charge separation time is found to be pulse-width-limited (<100 fs). Due to charge separation in these nanocomposites, an increase (2.6 fold) of photocurrent under visible light illumination is obtained. The fundamental understanding of the charge transfer dynamics affords new opportunities to design efficient light-harvesting systems based on inorganic-organic hybrids.

Perspective of dye-encapsulated conjugated polymer nanoparticles for potential applications

“…As a proof of this electron transfer process, photocatalysis is improved from 55% for pure P3HT PNPs to 90.6% for P3HT PNPs-Au NPs hybrid system under visible light irradiation. Considering the high electron-accepting property of reduced graphene oxide (r-GO), MEH-PPV PNP/r-GO has been designed for more efficient electron transfer [58]. The appearance of broad bleach centred at 635 nm in transient spectroscopic study confirms the electron transfer from PNP to r-GO.…”

Unique p–n Heterostructured Water‐Borne Nanoparticles Exhibiting Impressive Charge‐Separation Ability

“…[38][39][40] However, it is notable that the photocurrent of the P3HT:PEG-C60 beads is over 3.2-fold higher than that of either the SDS-or C 16 E 10 -based NPs synthesized under the H-concentrationc onditions (Figure 16 b, left side). [38][39][40] However, it is notable that the photocurrent of the P3HT:PEG-C60 beads is over 3.2-fold higher than that of either the SDS-or C 16 E 10 -based NPs synthesized under the H-concentrationc onditions (Figure 16 b, left side).…”

“…Figure16b exhibits the current-voltage (I-V)r elationships for the photoresponseo ft he three different systems at bias voltages of À3a nd 3V .T he study was performed for fabricated indium tin oxide (ITO)/MoO 3 /water-bornec olloids/LiF/Al devices under illumination atA M1.5G 100 mW cm À2 .A ll devices were more sensitive to light illumination if ap ositive bias was applied, which implies that chargec arriers are effectively produced during visible light irradiation at high bias voltages; thus, they determine the current and cause the current to increase. [38][39][40] However, it is notable that the photocurrent of the P3HT:PEG-C60 beads is over 3.2-fold higher than that of either the SDS-or C 16 E 10 -based NPs synthesized under the H-concentrationc onditions (Figure 16 b, left side). In addition, if we used the particles with the optimized conditions for am ore precise comparison (P3HT:2 0mgmL À1 ,P C 61 BM:2 0mgmL À1 ,a nd sur- Figure 12.…”

Ultrafast Relaxation Processes of Conjugated Polymer Nanoparticles in the Presence of Au Nanoparticles

“…The appearance of an extra component and the decrease in radiative processes of the decay dynamics in presence of Au NPs suggest the charge transfer process in polymer/Au NP hybrid system. The photo‐generated electron can readily transfers to the Au NP (Figure B) because the Fermi level of Au NP lies between the band gaps of polymer nanoparticles . Analysis suggests that a very fast electron transfer process is possible from PNP to Au nanoparticles in the polymer‐Au hybrid systems.…”

“…Materials and Synthesis : Preparation of MEH‐PPV PNPs, Au NP was carried out according to the methods described elsewhere . Briefly, the details have been provided in supporting information.…”