Energy transfer from an individual silica nanoparticle to graphene quantum dots and resulting enhancement of photodetector responsivity

Abstract

Förster resonance energy transfer (FRET), referred to as the transfer of the photon energy absorbed in donor to acceptor, has received much attention as an important physical phenomenon for its potential applications in optoelectronic devices as well as for the understanding of some biological systems. If one-atom-thick graphene is used for donor or acceptor, it can minimize the separation between donor and acceptor, thereby maximizing the FRET efficiency (EFRET). Here, we report first fabrication of a FRET system composed of silica nanoparticles (SNPs) and graphene quantum dots (GQDs) as donors and acceptors, respectively. The FRET from SNPs to GQDs with an EFRET of ∼78% is demonstrated from excitation-dependent photoluminescence spectra and decay curves. The photodetector (PD) responsivity (R) of the FRET system at 532 nm is enhanced by 100∼101/102∼103 times under forward/reverse biases, respectively, compared to the PD containing solely GQDs. This remarkable enhancement is understood by network-like current paths formed by the GQDs on the SNPs and easy transfer of the carriers generated from the SNPs into the GQDs due to their close attachment. The R is 2∼3 times further enhanced at 325 nm by the FRET effect.

Photodetecting Heterostructures from Graphene and Encapsulated Colloidal Quantum Dot Films

“…22 This effect is expected to be minor compared to the external illumination, however, due to the low luminescent quantum yield of the ECQD film, as confirmed by the significant decrease in lifetime compared to the original ECQDs in solution, 11 a result of the film deposition process. 12 Besides, RET between the optically active defects on the silica shell surface and the graphene is only active for wavelengths below 380 nm (<3.26 eV), 17 whereas here the excitation wavelength is 488 nm (2.54 eV).…”

Graphene Quantum Dot Solid Sheets: Strong blue-light-emitting & photocurrent-producing band-gap-opened nanostructures

“…Therefore, we have monitored the PL decay curve of the acceptor system at 440 nm and compared it with the PL decay curve of the donor-acceptor mixture system to confirm the energy transfer mechanism. It has been reported that the average lifetime value of the mixture system is usually higher than the average lifetime value of the acceptor system because the charge carriers that are photoexcited in the donor system are non-radiatively transferred to the acceptor system and excite the acceptor system to produce emission; therefore, naturally, a longer lifetime value results 45 . In our work, we have obtained an average lifetime value of 7.85 ns from the mixture sample, which is higher than the acceptor systems’ average lifetime value of 6.03 ns (obtained from the PL decay curves shown in Supplementary Fig.…”

“…There are many reports on using graphene as an active light-absorbing layer, both individually and in combination with other organic/inorganic systems 45 , 58 – 60 . Here, we present a fully carbon-based photoconducting electrode prepared using GQD solid sheets as active material.…”

Graphene-Based Semiconductor Heterostructures for Photodetectors

“…This PD showed ~0.5 A/W R , 10 11 cm·Hz 1/2 /W D* , ~95 dB linear dynamic range (LDR), and 100 μs response time. Recently, PDs composed of silica NPs and graphene QDs as donors and acceptors were well operated based on Förster resonance energy transfer (FRET) mechanism, as shown in Figure 11 a–c [ 86 ]. Under reverse bias at 532 nm, the R of the FRET system was more than three times greater than that of the PD containing only graphene QDs, as shown in Figure 11 d. This performance improvement was interpreted by the network-like current paths formed by the graphene QDs on the silica NPs and easy transfer of the carriers generated from the silica NPs into the graphene QD due to their close attachment.…”

“…The use of one-atom-thick GQDs for acceptors can minimize R 0 and maximize the contacting area of the acceptors and the donors; ( c ) Schematic of the PD structure composed of the FRET system sandwiched between single-layer graphene sheets; ( d ) Responsivities of SNPs, GQDs, and SNPs/GQDs hybrid as functions of bias voltage, excited at 532 nm. Reproduced with permission for Figure 11 a–d from 2016 Scientific Reports [ 86 ].…”