ScholarWorks@성균관대학교

초록

Near-bandgap photon recycling via distributed Bragg reflector (DBR) offers a promising strategy for maximizing light-harvesting efficiency of photoelectrochemical (PEC) cells with the minimum charge recombination. However, most DBR films require alternating deposition of inorganic layers via high-vacuum equipment. Herein, all-solution-based DBR films, integrated via block copolymer (BCP) self-assembly, are precisely tailored for various target wavelengths in the visible range. Using interfacial engineering of symmetric-confinement, lamella-forming polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) is self-assembled into a defect-free multilayer nanostructure oriented parallel to the substrates. When a weak hydroxy acid, lactic acid (LA), is incorporated into the 2VP units, the P2VP domains are favorably swollen and protonated; this causes the lamellar structures to become more asymmetric, whereas uniaxially sharp interfaces between the lamellar microdomains are retained. The reflected wavelength (lambda m) for the BCP-based DBR films is cooperatively tuned by controlling the cross-linking density in the P2VP domains immediately before the LA incorporation. The narrow-width, high-reflectance BCP-based DBR films are integrated into the rear of the BiVO4 photoanodes to scrutinize the optimal lambda m for the best PEC performance. A remarkable increase in the current density is attributed to the redshift of the effective working wavelengths in the BiVO4 photoanode during the photon-recycling process.

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