Modulating FRET in Organic–Inorganic Nanohybrids for Light Harvesting Applications

Abstract

The energy transfer efficiencies of organic–inorganic nanohybrids comprised of two structurally similar squaraine dyes and CdSe nanoparticles were studied in detail and compared. Carbazole based unsymmetrical squaraine dyes (CTSQ-1 and CTSQ-2) having modified absorption characteristics were considered for modulating the effect of the overlap integral on energy transfer rate with the designed QDs. CTSQ-2 with ∼1.75 times higher molar extinction coefficient and 35 nm red-shift in absorption resulted in an ∼2.4 times faster energy transfer rate with QD. The calculated energy transfer rates (k T = 1.35 × 108 s–1 and 3.26 × 108 s–1 respectively for QD:CTSQ-1 and QD:CTSQ-2 nanohybrids) are at least one order of magnitude higher than both radiative (k r = 5.97 × 106 s–1) and nonradiative decay rate constants (k nr = 1.89 × 107 s–1) of QDs yielding very high FRET efficiency. The Stern–Volmer analysis of the quenching data indicated mainly static interaction of dyes with the QDs thus suggesting formation of organic–inorganic nanohybrids. When incorporated in dye-sensitized solar cells, the nanohybrids with 93% FRET efficiency, exhibited an overall 43% improvement in the photovoltaic performance. Among the two architectures employed for device fabrication the one with the smallest donor–acceptor distance delivered the best performance. Due to increased contribution from QDs, the IPCE spectra clearly indicate panchromatic response from the visible to NIR region. Thus, photovoltaic performance of NIR absorbing dyes were successfully improved by constructing panchromatic organic–inorganic nanohybrid materials.

Highly efficient FRET from aggregation-induced emission to BODIPY emission based on host–guest interaction for mimicking the light-harvesting system

“…1,2 FRET is widely studied and proved to be a powerful spectroscopic technique to accurately measure the distance between two uorescent sources at the nanometer scale, 3,4 enabling the study of molecular conformations 5 and interaction dynamics. 6 Moreover, FRET is a core phenomenon in photosynthesis, 7,8 organic photovoltaics, 9 lighting sources, 10,11 biosensing, [12][13][14] or drug delivery tracing. 15 Furthermore, for practical applications, two requirements are necessary for the FRET process to occur: (1) a substantial overlap of the donor emission spectrum with the acceptor absorption; (2) an appropriate linker and distance between the donor and the acceptor.…”

Exploring dynamics of resonance energy transfer in hybrid Quantum Dot Sensitized Solar Cells (QDSSC)

“…It is seen that the increase in J sc contributes majorly to the efficiency enhancement compared to the slight increase of V oc of the hybrid cell. This also supports energy transfer between GQD and CdSe leading to more excited states in CdSe driving more electrons to the conduction band of TiO 2 resulting in increased photocurrent generation [24]. From table 1 it is seen that the light harvesting, which was ineffective due to low quantum yield of GQD (5.26%) is made effective by transferring photons to CdSe (QY-34%) in the hybrid sample.…”

Corrosion prevention of commercial alloys by air-water interface grown, edge on oriented, ultrathin squaraine film

“…GIXD pattern of SQR film did not show any peak. However, powder XRD displayed two intense peaks at 15.96° and 24.57°, which could be indexed as (h00) and (0k0) diffraction peak of SQR 23,26 . The interplanar spacing of (010) planes of SQR film was found to be 0.36 nm.…”