Photoinduced fluorescence enhancement and energy transfer effects of quantum dots porous silicon

Abstract

We investigate photoinduced fluorescence enhancement (PFE) and energy transfer effects of surfactant capped Cd/Se core and CdSe/ZnS core/shell quantum dots (QD) that emit at 630‐650 nm adsorbed in and onto porous silicon (PSi) single layer films and microcavity devices. Evidence is presented for fluorescence resonance energy transfer (FRET) from the QD (emitter) to mesoPSi nanostructures (acceptor) that photoluminess between 650‐850 nm. We also observe a strong PFE of QD emission adsorbed into meso porous silicon (mesoPSi) under continuous irradiation with 532 nm excitation light. New insight into the mechanism of PFE is gleaned from studies of PSi pore size and surface chemistry including native, H2O2, UV‐ozone, and thermal oxides, and aminosilane coated thermal oxide mesoPSi. These treatments alter the photoluminescent characteristics of the mesoPSi and QD. The PFE effect on QD PL is largest on thermally oxidized microcavities. PFE is considerably weaker for CdSe QD adsorbed onto macroPSi, silicon wafer surfaces and especially for ZnS capped QD suggesting the PFE effect requires a close interaction of the QD core with oxidized substrate. It is plausible that mesoPSi (10‐20 nm dia) mediates a more intimate contact compared to macro or planar Si wafer. The PFE effect dynamically increases the QD PL by passivating nonradiative state through oxidation and possibly through increasing the lifetime of nonradiative trapped state by coupling to surface vibrations. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Development of l-lactate dehydrogenase biosensor based on porous silicon resonant microcavities as fluorescence enhancers

“…3(b) shows that the emission intensity using MC-2 was 10-and 5-fold higher than using single layer and detuned MC, respectively. This is in agreement with previous studies showing that a microcavity featuring a good spectral alignment with the maximum emission of the emitting molecule enhances the emission intensity of the immobilised fluorophore (DeLouise and Ouyang, 2009;Palestino et al, 2009). When we partially masked the surface of the resazurin-modified MC-2 during 10 min exposure to LDH (Fig.…”

“…Specifically, pSi with a microcavity structure offers signal amplification for fluorescence or luminescence-based detection systems. This is because the microcavity, which is a multilayer consisting of alternating porosities and a spacer layer in between, is able to enhance the emission of a fluorophore confined in the porous structure according to the Purcell effect (DeLouise and Ouyang, 2009;Koenderink, 2010;Poitras et al, 2003;Purcell, 1946;Qiao et al, 2010;Setzu et al, 2000). This particular pSi architecture has therefore been applied to fluorescence biosensor applications (Krismastuti et al, 2014;Palestino et al, 2008Palestino et al, , 2009Sciacca et al, 2009).…”

Enhancement of QDs' fluorescence based on porous silicon Bragg mirror

“…In biomedical field, QDs have been used as fluorescent tags in biomarkers and fluorescent probes in biomolecule detections [6,7]. In recent years, researchers have combined waveguide or photonic crystals with QDs, and fabricated devices with excellent properties [8][9][10][11]. Porous silicon (PSi) is a material with good biocompatibility, in addition, large internal surface areas, capability for size-selective filtering, ease of face functionalization, and can fabricate various types photonic devices are characters it has [12][13][14], these advantages have made PSi attract great interests in biosensing [15][16][17].…”

Biomolecule detection in porous silicon based microcavitiesviaeuropium luminescence enhancement

“…13,14 Previous reports have established that besides being sensitive to changes in the optical thickness of the spacer layer, [14][15][16] pSi microcavities (pSiMC) are an excellent host-matrix for luminescent molecules since they both sharpen and amplify the emission. 10,[17][18][19][20][21][22][23] Biosensors can exploit this effect by monitoring target analytes or molecules either directly by their emission or via an additional luminescent label. 8 Recent work investigating the performance of pSiMCs for uorescence based detection include the ones conducted by Palestino, et al 18 The performance of the pSiMC structure for emission enhancement was performed by comparing the uorescence intensities between the microcavity and other pSi structures (i.e.…”