Light-harvesting host–guest antenna materials for quantum solar energy conversion devices

Abstract

In natural photosynthesis, light is absorbed by photonic antenna systems consisting of a few hundred chlorophyll molecules. These devices allow fast energy transfer from an electronically excited molecule to an unexcited neighbor molecule in such a way that the excitation energy reaches the reaction center with high probability. Trapping occurs there. Systems with similar properties can be prepared by enclosing dyes inside a microporous material and by choosing conditions such that the cavities are able to uptake only monomers but not aggregates. The materials we discuss generally consist of cylindrical zeolite L crystals, in the size range of 30-7000 nm, the channels of which are filled with dye molecules. The synthesis is based on the fact that molecules can diffuse into individual channels. In some cases it is desirable to modify the channel openings afterwards by adding a closure molecule. Functionalization of the closure molecules allows fine-tuning of, for example, wettability, refractive index, and chemical reactivity. The supramolecular organization of the dyes inside the channels is a first stage of organization. It allows light harvesting within a certain volume of a dye-loaded nanocrystalline zeolite and radiationless transport to both ends of the cylinder or from the ends to the center. The second stage of organization is the coupling to an acceptor or donor stopcock fluorophore at the ends of the zeolite L channels, which can trap or inject electronic excitation energy. The third stage of organization is the coupling to an external device via a stopcock intermediate. Another host-guest system, which will be shortly presented, is zeolite A containing silver sulfide. Due to the small dimensions of the cages of zeolite A it is possible to stabilize Ag 2 S monomers and dimers. In contrast to bulk silver sulfide these small particles show photoluminescence in the visible. In both host-guest systems interesting optical phenomena such as laser action are observed. The wide-ranging tunability of these highly organized materials offers fascinating new possibilities for exploring excitation energy transfer phenomena, and challenges for developing new photonic devices for solar energy conversion and storage.

Organization of Zeolite Microcrystals for Production of Functional Materials

“…50 The monolayers of vertically oriented fluorophore-incorporating cylindrical zeolite-L crystals gave anisotropic photoluminescence (dichroic ratio ) 8.9), 21 which is higher than the previously reported value (4.5) from the fluorescent polymer-incorporating mesoporous silica. 51 Thus, the uniformly aligned mono-and multilayers of zeolite crystals can also be used as media for generation of anisotropic photoluminescence, 21 supramolecularly organized light-harvesting systems, 35,52 and nonlinear optical films. 53 The micropatterned monolayers can be used as high-throughput combinatorial catalysts and lowdielectric packing materials for integrated circuits.…”

Energy Collection, Transport, and Trapping by a Supramolecular Organization of Dyes in Hexagonal Zeolite Nanocrystals

“…[22] Furthermore, such crystals can act as nanolasers, see Figure 2a bottom, where the dye molecules start to laze by increasing the excitation power. [23] Mixed-dye materials consist of zeolite L crystals randomly filled with different dye molecules. This can be realized when the dyes enter the channels at about the same speed.…”

Effect of Method on Monolayer Assembly of Zeolite Microcrystals on Glass with Molecular Linkages

“…Closely packed and uniformly aligned monolayers of zeolite microcrystals on various substrates [1,2] can serve as precursors for molecular sieve membranes, [3][4][5] low dielectric materials, [6][7][8] supramolecular energy transfer systems, [9][10][11] nonlinear optical films, [12][13][14][15] anisotropic photoluminescent films, [16] other advanced materials [17,18] such as imaging and data storage media, [19] light energy harvesting devices, [20][21][22] and electrode modifiers [23]. The methods for monolayer assembly that have been explored so far are reflux and stirring (RS), [24][25][26] sonication (SO), [27] sonication with stacking (SWS), [27] and rubbing (RUB).…”