Extending the Lasing Wavelength Coverage of Organic Semiconductor Nanofibers by Periodic Organic–Organic Heteroepitaxy

Abstract

Organic–organic heteropitaxy based on alternating and periodic deposition of para-sexiphenyl and alpha-sexithiophene on muscovite mica enables the fabrication of organic semiconductor nanofibers capable of random lasing with multiband emission and operating in the monomolecular recombination regime at room temperature

Optical transition energies of isolated molecular monomers and weakly interacting two-dimensional aggregates

“…Furthermore, the physical properties associated with organic crystal structures are usually highly anisotropic [7][8][9][10]. This circumstance can be utilized, for instance, by adjusting molecular alignments to optimally absorb photons in OSCs [11] or to enable lasing operation of multilayer nanofibers [12]. Exploring and, consequently, exploiting these structure-property relations are thus necessary steps to achieve economically worthwhile device efficiencies.…”

Correlated electron–hole plasma in organometal perovskites

“…The microscopic processes involved in the stimulated light emission in a semiconductor are also different if an exciton gas or a plasma of unbound electrons and holes are involved, primarily due to the different way to accumulate for population inversion in Bose and Fermi distributions. In organics, an incoherent exciton population is generated following optical excitation; stimulated emission requires the annihilation of an exciton and the generation of a ground state vibration, very similar to a molecular three-level system 32,33 . In inorganic semiconductors, light amplification at room temperature mostly occurs from electron-hole recombination in a conducting plasma.…”

Organic van der Waals Epitaxy versus Templated Growth by Organic–Organic Heteroepitaxy

“…Recently, it has also been demonstrated that the described concept of an alternated deposition of multiple molecular species represents a powerful approach to achieve nanofiber lasing with ultrahigh bandwidth [58]. Based on the p-6P/6T material couple, the wavelength coverage of organic nanofibers' lasing could be extended from the deep blue to the red-orange, and it has been shown that bimolecular recombination can be suppressed.…”

“…Based on the p-6P/6T material couple, the wavelength coverage of organic nanofibers' lasing could be extended from the deep blue to the red-orange, and it has been shown that bimolecular recombination can be suppressed. excited-state recombination regime can be achieved by periodic organic-organic heteroepitaxy [58]. The first monolayer (ML) of 6T homogeneously covers the p-6P fibers, which becomes visible by green fluorescence.…”

“…The optical emission spectrogram in Figure 11.13(a) highlights the presence of strong intensity fluctuations along the LNA. The spectral shape displays a complex fringe pattern that can be ascribed to multipath interference realized along the LNA, enabled by backreflections at the breaks positions in the presence of waveguide-amplified spontaneous emission [58]. A representative emission spectrum that was recorded at position (i) is indicated in Figure 11.13(b).…”