Inducing Charge Separation in Solid-State Two-Dimensional Hybrid Perovskites through the Incorporation of Organic Charge-Transfer Complexes.

Two-dimensional (2D) hybrid perovskites make up an emerging class of materials for optoelectronic applications in which inorganic octahedral layers are separated by nonconductive large organic cations. This leads to a high-dimensional and dielectric confinement and hence a high exciton binding energy, which severely limits their application in devices in which charge carrier separation is required. In this work, we achieve improved charge separation by replacing nonconductive organic cations with organic charge-transfer complexes consisting of a pyrene donor and a tetracyanoquinodimethane acceptor. Steady-state absorption measurements show that these materials exhibit optical features that match with the absorption of the organic charge-transfer complexes. Using microwave conductivity and femtosecond transient absorption, we show that photoexcitation of these charge-transfer states leads to long-lived mobile charges in the inorganic layers. While the efficiency of charge separation is relatively low, these experiments demonstrate that it is possible to induce charge separation in solid-state 2D perovskites by engineering the organic layer.

Towards 2D layered hybrid perovskites with enhanced functionality: introducing charge-transfer complexes via self-assembly.

This study broadens the family of 2D layered perovskites by demonstrating that it is possible to self-assemble organic charge-transfer complexes in their organic layer. Organic charge-transfer complexes, formed by combining charge-donating and charge-accepting molecules, are a diverse class of materials that can possess exceptional optical and electronic properties.

Direct arylation as a versatile tool towards thiazolo[5,4-d]thiazole-based semiconducting materials.

A series of thiazolo[5,4-d]thiazole-based small molecule organic optoelectronic materials is synthesized via a straightforward microwave-activated Pd-catalyzed C-H arylation protocol. The procedure allows us to obtain extended 2,5-dithienylthiazolo[5,4-d]thiazole chromophores with tailor-made energy levels and absorption patterns, depending on the introduced (het)aryl moieties and the molecular (a)symmetry, by shortened sequences without organometallic intermediates. The synthesized materials can be applied as either electron donor or electron acceptor light-harvesting materials in molecular bulk heterojunction organic solar cells.