Charge Transfer Excitons at van der Waals Interfaces

Zhu, Xiaoyang; Monahan, Nicholas R.; Gong, Zizhou; Zhu, Haiming; Williams, Kristopher; Nelson, Cory A.

doi:10.1021/jacs.5b03141

Cited by 268 publications

(315 citation statements)

References 77 publications

Supporting

Mentioning

297

Contrasting

Order By: Relevance

“…273,274,290,291,298,303312,320,321,323,325334 Still it is taken for granted that they should be utilized in the form of nothing but thin films. Considering the high efficiency of photoconduction, the salts discussed in this account or related compounds may include materials of choice for photovoltaic cells utilized as single crystals with the aid of optical doping.…”

Section: Resultsmentioning

confidence: 99%

Development of a Control Method for Conduction and Magnetism in Molecular Crystals

Naito

2016

Bulletin of the Chemical Society of Japan

View full text Add to dashboard Cite

This study concerns development of a non-destructive method to control conduction and magnetism of molecular solids such as single crystals of charge-transfer complexes. The method is named “optical doping”, where appropriate irradiation is utilized under ambient conditions. Owing to this feature, it can be applied to a wide range of substances while measuring the properties during the control. In addition, the method adds unique conduction and magnetic properties to common insulators. Unlike other doping methods, optical doping only affects the properties and/or structures of the irradiated part of a sample while leaving the rest of the sample unchanged. There are two patterns in the optical doping. Irreversible optical doping produces junction-structures on the single molecular crystals, which exhibit characteristic behavior of semiconductor devices such as diodes and varistors. Reversible optical doping produces “giant photoconductors” and “photomagnetic conductors” by realizing unprecedented metallic photoconduction. In the latter case, localized spins are also excited to produce a Kondo system, where carriers and localized spins interact with each other. Not only the control of conduction and magnetism, the optical doping has realized the observation of physical properties in molecular crystals hardly observed under any thermodynamic condition.

show abstract

Section: Resultsmentioning

confidence: 99%

Development of a Control Method for Conduction and Magnetism in Molecular Crystals

Naito

2016

Bulletin of the Chemical Society of Japan

View full text Add to dashboard Cite

show abstract

“…38,39 One of the best studied of this class of compounds is rhodamine 6G (Rh6G), which has both a high quantum yield for fluorescence and a large cross section for Raman scattering. Wavelength shifts in the absorbance and emission spectra of Rh6G imply that aggregates form in solution at higher concentrations, as suggested by either exciton [66][67][68] or excimer theory. 69 In thin films, the same electronic spectroscopic effects are also observed, and are a function of film thickness.…”

Section: Introductionmentioning

confidence: 98%

A comparison of SERS and MEF of rhodamine 6G on a gold substrate

Kohr

Karawdeniya

Dwyer

et al. 2017

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

Rhodamine 6G is spin-cast onto gold surfaces and the reflectance, emission, excitation, and SERS spectra are reported. Electron microscopy shows that the particle sizes of the gold are uniform for all preparations. Reflection spectra show that the Rh6G aggregates for thicker films and that the gold plasmon band shifts due to the refractive index change on the surface. The intensity of the SERS spectra increases with increasing surface coverage but the rate of change modulates between submonolayer and multilayer surface densities. The emission spectra behave unexpectedly as a function of Rh6G coverage. At submonolayer coverage the emission is relatively strong, decreases as the surface density increases to a monolayer, and then increases as the Rh6G thickness increases. Excitation spectra demonstrate that the emitting species at low surface density is monomeric but for thicker layers the excited state responsible for emission is Rh6G aggregates. For the thicker films, the Rh6G acts as its own dielectric layer for metal enhanced fluorescence of the aggregates.iii ACKNOWLEDGMENTS

show abstract

“…The emitted luminescence is dispersed by a single grating spectrometer and recorded with a charge coupled device (CCD) camera with a combined spectral resolution of about 0.2 meV. Notably, the signal that we interpret to stem from interlayer excitons [IX in Figure 1( [47]. In particular, the dissociation of the hot electron-hole pairs at the junction can be assumed to be faster than the formation of intralayer excitons.…”

mentioning

confidence: 97%

Long-Lived Direct and Indirect Interlayer Excitons in van der Waals Heterostructures

et al. 2017

View full text Add to dashboard Cite

We investigate the photoluminescence of interlayer excitons in heterostructures consisting of monolayer MoSe2 and WSe2 at low temperatures. Surprisingly, we find a doublet structure for such interlayer excitons. Both peaks exhibit long photoluminescence lifetimes of several ten nanoseconds up to 100 ns at low temperatures, which verifies the interlayer nature of both.The peak energy and linewidth of both show unusual temperature and power dependences.In particular, we observe a blue-shift of their emission energy for increasing excitation powers.At a low excitation power and low temperatures, the energetically higher peak shows several spikes. We explain the findings by two sorts of interlayer excitons; one that is indirect in real space but direct in reciprocal space, and the other one being indirect in both spaces. Our results provide fundamental insights into long-lived interlayer states in van der Waals heterostructures with possible bosonic many-body interactions.Keywords: van der Waals heterostructure, indirect excitons, interlayer exciton, photoluminescence, exciton lifetime, transition metal dichalcogenides; 2 Semiconductor heterostructures (HS) are very often the foundation for the observation of novel phenomena in both fundamental science as well as device applications. The electrical and optical properties of such HS can be engineered in a wide range resulting in precisely tailored functionalities. Of particular interest are optically active HS facilitating many device applications such as photo-detectors, solar cells, light-emitting diodes or lasers and fostering the observation of many-body driven quantum phenomena found in systems with reduced dimensionality such as quantum wells or quantum dots. Excitons are electron-hole pairs coupled by attractive Coulomb interaction which results in a ground state with a reduced energy compared to the corresponding single-particle energies. Exciton ensembles exhibit an intriguing interaction driven phase diagram with different classical and quantum phases including quantum liquids and solids [1][2][3]. The bosonic nature of excitons enables these composite particles even to condensate into macroscopic ground state wave functions forming a Bose-Einstein condensate (BEC) [4].Ensembles of indirect a.k.a. interlayer excitons (IXs) are particularly fascinating systems to explore such classical and quantum phases of interacting bosonic ensembles. IXs are composite bosons that feature enlarged lifetimes due to the reduced overlap of the electronhole wave functions resulting in dense IX ensembles that are thermalized to the lattice temperature. Besides IX ensembles in III-V HS [5][6][7][8][9][10][11][12][13][14][15], hetero-bilayers prepared from semiconducting transition metal dichalcogenides (TMDs) exhibit superior potential for studying interacting IX ensembles [3,[16][17][18][19][20][21][22][23][24][25] with intriguing spin-and valley-properties [26][27][28]. At the same time, TMDs are truly two-dimensional (2D) crystals coupled to each other or to substrat...

show abstract

Charge Transfer Excitons at van der Waals Interfaces

Cited by 268 publications

References 77 publications

Development of a Control Method for Conduction and Magnetism in Molecular Crystals

Development of a Control Method for Conduction and Magnetism in Molecular Crystals

A comparison of SERS and MEF of rhodamine 6G on a gold substrate

Long-Lived Direct and Indirect Interlayer Excitons in van der Waals Heterostructures

Contact Info

Product

Resources

About