The vast majority of perovskite solar cell research has focused on organic–inorganic lead trihalide perovskites; herein, we present working inorganic CsPbI3perovskite solar cells for the first time.

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A large number of graphene molecules, or large polycyclic aromatic hydrocarbons (PAHs), have been synthesized and display various optoelectronic properties. Nevertheless, their potential for application in photonics has remained largely unexplored. Herein, we describe the synthesis of a highly luminescent and stable graphene molecule, namely a substituted dibenzo[hi,st]ovalene (DBO 1), with zigzag edges and elucidate its promising optical‐gain properties by means of ultrafast transient absorption spectroscopy. Upon incorporation of DBO into an inert polystyrene matrix, amplified stimulated emission can be observed with a relatively low power threshold (ca. 60 μJ cm−2), thus highlighting its high potential for lasing applications.

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A π-extended double [7]carbohelicene 2 with fused pyrene units was synthesized, revealing considerable intra- and intermolecular π–π interactions as confirmed with X-ray crystallography. As compared to the previous double [7]carbohelicene 1 , the π-extended homologue 2 demonstrated considerably red-shifted absorption with an onset at 645 nm ( 1 : 550 nm) corresponding to a smaller optical gap of 1.90 eV ( 1 : 2.25 eV). A broad near-infrared emission from 600 to 900 nm with a large Stokes shift of ∼100 nm (2.3 × 10 3 cm –1 ) was recorded for 2 , implying formation of an intramolecular excimer upon excitation, which was corroborated with femtosecond transient absorption spectroscopy. Moreover, 2 revealed remarkable chiral stability with a fairly high isomerization barrier of 46 kcal mol –1 , according to density functional theory calculations, which allowed optical resolution by chiral HPLC and suggests potential applications in chiroptical devices.

The non‐covalent affinity of photoresponsive molecules to biotargets represents an attractive tool for achieving effective cell photo‐stimulation. Here, an amphiphilic azobenzene that preferentially dwells within the plasma membrane is studied. In particular, its isomerization dynamics in different media is investigated. It is found that in molecular aggregates formed in water, the isomerization reaction is hindered, while radiative deactivation is favored. However, once protected by a lipid shell, the photochromic molecule reacquires its ultrafast photoisomerization capacity. This behavior is explained considering collective excited states that may form in aggregates, locking the conformational dynamics and redistributing the oscillator strength. By applying the pump probe technique in different media, an isomerization time in the order of 10 ps is identified and the deactivation in the aggregate in water is also characterized. Finally, it is demonstrated that the reversible modulation of membrane potential of HEK293 cells via illumination with visible light can be indeed related to the recovered trans→cis photoreaction in lipid membrane. These data fully account for the recently reported experiments in neurons, showing that the amphiphilic azobenzenes, once partitioned in the cell membrane, are effective light actuators for the modification of the electrical state of the membrane.

Aviation and space applications can benefit significantly from lightweight organic electronics, now spanning from displays to logics, because of the vital importance of minimising payload (size and mass). It is thus crucial to assess the damage caused to such materials by cosmic rays and neutrons, which pose a variety of hazards through atomic displacements following neutron-nucleus collisions. Here we report the first study of the neutron radiation tolerance of two poly(thiophene)s-based organic semiconductors: poly(3-hexylthiophene-2,5-diyl), P3HT, and the liquid-crystalline poly(2,5-bis (3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene), PBTTT. We combine spectroscopic investigations with characterisation of intrinsic charge mobility to show that PBTTT exhibits significantly higher tolerance than P3HT. We explain this in terms of a superior chemical, structural and conformational stability of PBTTT, which can be ascribed to its higher crystallinity, in turn induced by a combination of molecular design features. Our approach can be used to develop design strategies for better neutron radiation-tolerant materials, thus paving the way for organic semiconductors to enter avionics and space applications.

Excitonic 0D and 2D lead-halide perovskites have been recently developed and investigated asnew materials for light generation [1] . Here we report broadband (> 1 eV) emission from newly synthesised zero-dimensional (0D) lead-free colloidal Cs3Bi2I9 nanocrystals. We investigate the nature of their emissive states as well as the relative dynamics which are currently hotly debated. In particular, we find that the broadband emission is made by the coexistence of emissive excitons and sub-bandgap emissive trap-states. Remarkably, we observe evidence of enhanced Raman scattering from the ligands when attached to the nanocrystals surface, an effect that we preliminary attribute to strong exciton-ligands electronic coupling in these systems.These authors contributed equally to this work.