Perovskite solar cells prepared by flash evaporation

A simple vacuum deposition method for the preparation of high quality hybrid organic-inorganic methylammonium lead iodide perovskite thin films is reported. When sandwiched in between organic charge transporting layers, such films lead to solar cells with a power conversion efficiency of 12.2%

Highly luminescent perovskite–aluminum oxide composites

In this communication we report on the preparation of CH3NH3PbBr3 perovskite/Al2O3 nanoparticle composites in a thin film configuration and demonstrate their high photoluminescence quantum yield. The composite material is solution-processed at low temperature, using stable alumina nanoparticle dispersions. There is a large influence of the alumina nanoparticle concentration on the perovskite morphology and on its photoluminescence

Efficient photovoltaic and electroluminescent perovskite devices

Planar diode structures employing hybrid organic-inorganic methylammonium lead iodide perovskites lead to multifunctional devices exhibiting both a high photovoltaic efficiency and good electroluminescence. The electroluminescence strongly improves at higher current density applied using a pulsed driving method

Advances in Perovskite Solar Cells

Organolead halide perovskite materials possess a combination of remarkable optoelectronic properties, such as steep optical absorption edge and high absorption coefficients, long charge carrier diffusion lengths and lifetimes. Taken together with the ability for low temperature preparation, also from solution, perovskite-based devices, especially photovoltaic (PV) cells have been studied intensively, with remarkable progress in performance, over the past few years. The combination of high efficiency, low cost and additional (non-PV) applications provides great potential for commercialization. Performance and applications of perovskite solar cells often correlate with their device structures. Many innovative device structures were developed, aiming at large-scale fabrication, reducing fabrication cost, enhancing the power conversion efficiency and thus broadening potential future applications. This review summarizes typical structures of perovskite solar cells and comments on novel device structures. The applications of perovskite solar cells are discussed

Deposition Kinetics and Compositional Control of Vacuum Processed CH3NH3PbI3 Perovskite

Halide perovskites have generated considerable research interest due to their excellent optoelectronic properties in the past decade. To ensure the formation of high quality semiconductors, the deposition process for the perovskite film is a critical issue. Vacuum based processing is considered a promising method allowing, in principle, also for large areas. One of the benefits of vacuum processing is the control over the film composition through the use of quartz crystal microbalances (QCMs) that in-situ monitor the rates of the components. In metal halide perovskites, however, one frequently employed component or precursor, CH3NH3I, exhibits non-standard sublimation properties. Here, we study in detail the sublimation properties of CH3NH3I and demonstrate that by correcting for its complex adsorption properties and by modeling the film growth, accurate predictions about the stoichiometry of the final perovskite film can be obtained

Advances in Perovskite Solar Cells

Organolead halide perovskite materials possess a combination of remarkable optoelectronic properties, such as steep optical absorption edge and high absorption coefficients, long charge carrier diffusion lengths and lifetimes. Taken together with the ability for low temperature preparation, also from solution, perovskite-based devices, especially photovoltaic (PV) cells have been studied intensively, with remarkable progress in performance, over the past few years. The combination of high efficiency, low cost and additional (non-PV) applications provides great potential for commercialization. Performance and applications of perovskite solar cells often correlate with their device structures. Many innovative device structures were developed, aiming at large-scale fabrication, reducing fabrication cost, enhancing the power conversion efficiency and thus broadening potential future applications. This review summarizes typical structures of perovskite solar cells and comments on novel device structures. The applications of perovskite solar cells are discussed

Charge Noise in Organic Electrochemical Transistors

Organic electrochemical transistors (OECTs) are increasingly studied as transducers in sensing applications. While much emphasis has been placed on analyzing and maximizing the OECT signal, noise has been mostly ignored, although it determines the resolution of the sensor. The major contribution to the noise in sensing devices is the 1/f noise, dominant at low frequency. In this work, we demonstrate that the 1/f noise in OECTs follows a charge-noise model, which reveals that the noise is due to charge fuctuations in proximity or within the bulk of the channel material. We present the noise scaling behavior with gate voltage, channel dimensions and polymer thickness. Our results suggest the use of large area channels in order to maximize the signal-to-noise-ratio (SNR) for biochemical and electrostatic sensing applications. Comparison with literature shows that the magnitude of the noise in OECTs is similar to that observed in graphene transistors, and only slightly higher compared to Carbon nanotubes and Silicon nanowire devices. In a model ion-sensing experiment with OECTs, we estimate crucial parameters such as the characteristic SNR and corresponding limit of detection

Increased conductivity of a hole transport layer due to oxidation by a molecular nanomagnet

Thin film transistors based on polyarylamine poly(N,N′-diphenyl-N,N′bis(4-hexylphenyl)-[1,1′biphenyl]-4,4′-diamine (pTPD) were fabricated using spin coating in order to measure the mobility of pTPD upon oxidation. Partially oxidized pTPD with a molecular magnetic cluster showed an increase in mobility of over two orders of magnitude. A transition in the mobility of pTPD upon doping could also be observed by the presence of a maximum obtained for a given oxidant ratio and subsequent decrease for a higher ratio. Such result agrees well with a previously reported model based on the combined effect of dipolar broadening of the density of states and transport manifold [email protected] [email protected]

Millisecond radiative recombination in poly(phenylene vinylene)-based light-emitting diodes from transient electroluminescence

The current and electroluminescence transient responses of standard poly(phenylene vinylene)-based light-emitting devices have been investigated. The electroluminescence time response is longer (milliseconds scale) than the current switch-off time by more than one order of magnitude, in the case of small area devices (<0.1 cm2). For large area devices ( ∼ 6 cm2) the electroluminescence decay time decreases from 1.45 ms to  ∼ 100 μs with increasing bias voltage. The fast current decay limits the electroluminescence decay at higher voltages. Several approaches are discussed to interpret the observed slow decrease of electroluminescence after turning off the bias. One relies upon the Langevin-type bimolecular recombination kinetics which is governed by the minority carriers (electrons), and another focuses on the slow release of trapped electrons as possible explanations. Additionally, we show that the device current density is mainly determined by the transport of the fastest carriers (holes)[email protected]

Nucleant layer effect on nanocolumnar ZnO films grown by electrodeposition

Different ZnO nanostructured films were electrochemically grown, using an aqueous solution based on ZnCl2, on three types of transparent conductive oxides grow on commercial ITO (In2O3:Sn)-covered glass substrates: (1) ZnO prepared by spin coating, (2) ZnO prepared by direct current magnetron sputtering, and (3) commercial ITO-covered glass substrates. Although thin, these primary oxide layers play an important role on the properties of the nanostructured films grown on top of them. Additionally, these primary oxide layers prevent direct hole combination when used in optoelectronic devices. Structural and optical characterizations were carried out by scanning electron microscopy, atomic force microscopy, and optical transmission spectroscopy. We show that the properties of the ZnO nanostructured films depend strongly on the type of primary oxide-covered substrate used. Previous studies on different electrodeposition methods for nucleation and growth are considered in the final discussion.Facultad de Ciencias Exacta