Solution processed perovskite semiconductors have developed rapidly over the past decade to yield excellent performance in both solar cell and light emitting diode devices. Both of these device types are prepared using similar materials and architectures, raising the possibility of perovskite based light emitting solar cells. Recent reports have indicated that some low band gap perovskite solar cells are able to emit infrared light efficiently, however, intermediate band gap perovskite solar cells which emit visible light have not, to the best of our knowledge been deliberately designed or extensively characterized. In this work, we have investigated the use of different electron transport layers in order to minimize energetic barriers to electron injection and extraction in methylammonium lead bromide (MAPbBr₃) films. We demonstrate that through appropriate band structure engineering, MAPbBr₃ can be used to make such “peroptronic” light-emitting solar cells, which simultaneously exhibit efficient solar cell power conversion efficiencies over 1% and 0.43 lm W⁻¹ green light emission.

A new donor–acceptor type small molecule with dithienothiophene and diketopyrrolopyrrole units has been synthesized for application in organic solar cells. In order to optimize the nanoscale morphology of the small molecule solar cells, additives such as 1,8-diiodooctane (DIO) and 1-chloronaphthalene (CN) are used. The use of CN significantly suppresses molecular aggregation and allows suitable phase separation, enhancing power conversion efficiency from 0.5% to 2.2%.

Hybrid organic–inorganic perovskites (HOIPs) have attracted considerable attention for their scientific and technological potential in photovoltaics and optoelectronic devices. Recently, two-dimensional (2D) HOIPs have become established as useful active layers for photovoltaic applications, offering adjustable electronic levels, high charge carrier mobilities, and simplicity of thin-film device fabrication. In this work, we describe the preparation of a new Cu-based 2D hybrid perovskite, with the structural formula (C₆H₁₀N₂)[CuCl₄], of which crystallographic, spectroscopic, optical and magnetic properties have been studied and analyzed. The compound exhibits dominant ferromagnetic interactions. Fits of the χ(T) data to the 2D-ferromagnetic layer model yielded C = 0.456(2) emu-K mol-Oe⁻¹ and J = 5.5(1). Analysis of electromagnetic absorption and reflectance properties through the visible and near-infrared indicate an optical band gap of 1.24 eV (absorption) or 1.23 eV (reflection) and a direct, spin-forbidden electronic transition giving rise to a strong absorption band centered at 740 nm, which allows it to absorb a large portion of the solar spectrum. Although the absorption coefficient is lower than lead halide perovskites, it is greater than 1000 cm⁻¹ throughout the visible spectrum up to 1000 nm, giving the material potential as a solar absorber if relatively thick (∼5 μm) films are used. The nature of the electronic transition and frontier electronic states were studied by DFT and reveal valence and conduction bands arising from repeating CuCl₄ square planar structural units composed of hybridized Cl 3p_x,y orbitals and Cu 3d_x²−y² orbitals. The electronic structure and optical properties indicate that the material might be able to serve as a non-toxic alternative to lead-based HOIPs in some applications.

The effect of solvent additives on the performance of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) field effect transistors (FETs) was investigated. Hole mobilities increased from 0.10 cm² V⁻¹ s⁻¹ for pristine devices to 0.73 or 0.71 cm² V⁻¹ s⁻¹, when TIPS-pentacene FETs were processed with diphenyl ether (DPE) or chloronaphthalene (CN), respectively. In order to examine the impact of additives on the surface morphology, molecular ordering and crystallinity of TIPS-pentacene, scanning electron microscopy (SEM), X-ray diffraction (XRD) and optical microscopy measurements were carried out. Appropriate amounts of additives were found to induce the formation of well-ordered crystalline domains in TIPS-pentacene films, resulting in enhanced hole transport as well as consistent device performance. Additionally, reduced contact resistances were observed in devices processed with additives compared to neat TIPS-pentacene FET devices. Our findings indicate that the use of solvent additives constitutes a new and effective methodology for the fabrication of OFETs with improved performance.

We report the design, fabrication, and characterization of high-performance, solution-processed hybrid (inorganic-organic) light emitting transistors (HLETs). The devices employ a high-mobility, solution-processed cadmium sulfide layer as the switching and transport layer, with a conjugated polymer Super Yellow as an emissive material in non-planar source/drain transistor geometry. We demonstrate HLETs with electron mobilities of up to 19.5 cm²/V s, current on/off ratios of >10⁷, and external quantum efficiency of 10⁻²% at 2100 cd/m². These combined optical and electrical performance exceed those reported to date for HLETs. Furthermore, we provide full analysis of charge injection, charge transport, and recombination mechanism of the HLETs. The high brightness coupled with a high on/off ratio and low-cost solution processing makes this type of hybrid device attractive from a manufacturing perspective.