Type-II core/shell nanoparticle induced photorefractivity

Abstract

We demonstrate engineering the photocharge generation efficiency of nanoparticles on the nanometer scale by using a type-II band-gap structure. Compared to bare CdSe cores, the dispersion of type-II core/shell nanoparticles in photorefractive polymer led to an average 100% increase in photocurrents. An improvement to the refractive-index construction time, and a near 100% enhancement to the two beam coupling net-gain coefficients and four-wave mixing internal diffraction efficiencies have been achieved at moderate biases.

Photorefractive polymers for holography

“…33 Li et al recorded the photorefractive performance enhancement resulting from the implementation of type II core/shell CdSe/CdTe nanoparticles compared to simple CdSe core-only particles in a PVK:DABM:ECZ:NP composite. 62 The gain and diffraction efficiency doubled through the addition of a shell layer and the response speed increased noticeably as well. The authors attribute these improvements to enriched free-carrier generation due to the shell layer energetics.…”

“…This performance barrier in many of these cases is the restriction placed on doping concentration due to aggregation by the nanoparticles which in turn affects their overall sensitization ability . Li et al recorded the photorefractive performance enhancement resulting from the implementation of type II core/shell CdSe/CdTe nanoparticles compared to simple CdSe core‐only particles in a PVK:DABM:ECZ:NP composite . The gain and diffraction efficiency doubled through the addition of a shell layer and the response speed increased noticeably as well.…”

Exciton-plasmon coupling mediated photorefractivity in gold-nanoparticle- and quantum-dot-dispersed polymers

“…5,13,14 Even though enormous efforts have been spent to enhance their PR performance by using surface engineered type-I and type-II core/shell QDs, limited success has been achieved at a cost of either a reduced response speed 15 or a restricted refractive-index modulation strength. 16 On the other hand, the surface plasmon in metallic nanoparticles (NPs) coupling with the exciton of QDs can dramatically enhance the subsequent photophysics of QDs, 17,18 opening a new approach to improve the performance of QD-based opto-electronic devices. The exciton-plasmon coupling could potentially tackle these drawbacks of PR polymers; however, its application in PR polymers has never been investigated before.…”

“…16,21 Au NPs with an extinction peak at the wavelength of 530 nm and an average particle size of 45 nm were synthesized by following a well-established recipe. 22 Figs.…”