Metal‐organic framework coordinated with cobalt ion as charge recombination retarder in dye‐sensitized solar cells

Abstract

The photoanode of the conventional dye-sensitized solar cell (DSSC) is modified, by depositing a layer of cobalt-metallic-ion-coordinated metal-organic framework (Co-MOF199) on top of the regular titanium-dioxide film. The results of electrochemical impedance spectrum (EIS) indicated that the presence of Co-MOF199 layer in the photoanode of DSSC brought about an increase in the electron recombination lifetime (time to the electrons to recombine with the cations) and, consequently, the increase in electron recombination resistance (R rec ) in the photoanode electrolyte interface. The increased recombination resistance is attributed to the efficient retardation of the rapid recombination between photo-induced electrons and transient cations in DSSC. These positive changes in the photoanode electrolyte interface of DSSC resulted in the increase in open-circuit voltage (V oc ), which accounts for the ultimate 20% enhancement in the power conversion efficiency η ð Þ, compared to the conventional DSSC. A total of six Co-MOF199 concentration variants of DSSC configurations coated by soaking and spin coating were fabricated, and it was observed that [TiO 2 + N3/Co-MOF199 (30 mM)/Pt] DSSC configuration

Photoelectroactive metal–organic frameworks

“…For instance, a Co MOF constructed from Co(NO 3 ) 2 ·6H 2 O and H 3 BTC deposited on a N3 dye-coated TiO 2 /FTO as the photoanode in a DSSC was reported to exhibit a PCE of 8.35%. 103 The Co MOF layer inhibited photo-induced electron recombination, thus increasing its lifetime, which led to a PCE enhancement by 20% in contrast to a photoanode without Co MOF under the same conditions. Using either ZIF-8 or UiO-66 with reduced graphene oxide (rGO) doped into TiO 2 to be coated onto indoline dye/FTO glass substrates as photoanodes reportedly showed PCEs of 7.33% for the former and 7.67% for the latter.…”

“…Notably, organic linkers of carboxylic acids such as terephthalic acid (H 2 BDC) [93][94][95] and its derivatives with functional groups (e.g., -NH 2 , -OH, -SH, -SCH 3 ), [96][97][98][99][100] trimesic acid (H 3 BTC), [101][102][103] and meso-tetraphenylporphine-4,4 ′ ,4 ′′ ,4 ′′′ -tetracarboxylic acid (H 2 TCPP) 57,84,104 were extensively exploited to construct photoelectroactive MOFs for photocatalysis and photovoltaics. The introduction of functional groups enabled the improvement of light absorption and extended wavelength utilization.…”

“…84,282,305 Intensive investigations have been focused on the exploration of novel photoanodes, CEs and improved electrolytes. 83,103,[306][307][308][309] MOF-based materials for DSSCs have been attracting increasing attention. For instance, a Co MOF constructed from Co(NO 3 ) 2 $6H 2 O and H 3 BTC deposited on a N3 dye-coated TiO 2 /FTO as the photoanode in a DSSC was reported to exhibit a PCE of 8.35%.…”