Chromophores face applicability limitations due to their natural tendency to aggregate, with a subsequent deactivation of their emission features. Hence, there has been a fast development of aggregation induced emission (AIE) emitters, in which non-radiative motional deactivation is inhibited. However, a fine control of their colloidal properties governing the emitting performance is fundamental for their application in thin film optoelectronics. In addition, ion-based lighting devices, such as light emitting electrochemical cells (LECs), requires the design of ionic AIE emitters, whose structure allows (i) an easy ion polarizability to assist charge injection and (ii) a reversible electrochemical behavior. To date, these fundamental questions have not been addressed. Herein, the hydrophilic/hydrophobic balance of a family of cationic tetraphenyl ethene (TPE) derivatives is finely tuned by chemical design. The hydrophilic yet repulsive effect of pyridinium-based cationic moieties is balanced with hydrophobic variables (long alkyl chains or counterion chemistry), leading to (i) a control between monomeric/aggregate state ruling photoluminescence, (ii) redox behavior, and (iii) enhanced ion conductivity in thin films. This resulted in a LEC enhancement with the first ionic AIE emitters, reaching values of 0.19 lm W⁻¹ at ca. 50 cd m⁻². Overall, this design rule will be key to advance ionic active species for optoelectronics.

A layer of fluorinated reduced graphene oxide (FrGO), as an alternative hole transport (HTL) in organic solar cells (OSCs) based on a PBDB-T:ITIC active layer, is reported. OSC configuration is ITO/HTL/PBDB-T:ITIC/PFN/FM; FM is Field’s metal, a eutectic alloy deposited at room atmosphere. PEDOT:PSS, FrGO/PEDOT:PSS, and FrGO are tested as HTLs; the average efficiencies of 8.8, 8.2, and 5.3%, respectively, are reached. Inhomogeneity of the FrGO layer is determined as the main factor that affects the photovoltaic behavior and stability. Device stability is very acceptable, sometimes with a superior behavior than data previously reported; FM also could potentially contribute to this enhanced stability.

Quasi‐2D perovskites provide new opportunities for lighting and display applications due to their high radiative recombination and excellent stability. However, seldom attention has been placed on their self‐stability/working operation under ambient storage. Herein, quasi‐2D perovskites/Polyethylene oxide (PEO) films are studied, showing an unforeseen photo‐brightening effect under ambient storage (i.e., an increase of the photoluminescence quantum yield from 55% to 74% after 100 days). In stark contrast, those stored under a dark/inert atmosphere show a significant decrease down to 38%. This counterintuitive phenomenon responds to the increasing radiative recombination rate caused by the passivation of the surface Br vacancies in the presence of physically adsorbed water molecules, as corroborated by in situ/ex situ X‐ray photoelectron spectroscopy and density functional theory calculations. Capitalizing on this surprising effect, stable light‐emitting diodes (LEDs) using quasi‐2D perovskites/PEO color filters are fabricated, realizing high stabilities of ≈400 h@10 mA under operating ambient conditions, representing a 20‐fold enhancement compared to LEDs with 3D counter partners. Hence, this study reveals a unique insight into the impact of water passivation on the optical/structural properties of quasi‐2D perovskite films, broadening their applications under operating ambient conditions.

Using scanning tunneling microscopy (STM) and spectroscopy (STS) at the liquid/solid interface, morphology evolution process and energetic level alignment of very thin solid films (thickness: <700 pm), of the low molecular weight molecule DRCN5T and DRCN5T:[70]PCBM blend are analyzed after applying thermal annealing at different temperatures. These films exhibit a worm-like pattern without thermal annealing (amorphous shape); however, after applying thermal annealing at 120 °C, the small molecule film domains crystallize verified by X-ray diffraction: structural geometry becomes a well-defined organized array. By using STS, the energy band diagrams of the semiconductor bulk heterojunction (blended film) at the donor-acceptor interface are determined; morphology and energy characteristics can be correlated with the organic solar cells (OSC) performance. When combining thermal treatment and solvent vapor annealing processes as described in previous literature by using other techniques, OSC devices based on DRCN5T show a very acceptable power conversion efficiency of 9.0%.