Conducting polymers (CPs), thanks to their unique properties, structures made on-demand, new composite mixtures, and possibility of deposit on a surface by chemical, physical, or electrochemical methodologies, have shown in the last years a renaissance and have been widely used in important fields of chemistry and materials science. Due to the extent of the literature on CPs, this review, after a concise introduction about the interrelationship between electrochemistry and conducting polymers, is focused exclusively on the following applications: energy (energy storage devices and solar cells), use in environmental remediation (anion and cation trapping, electrocatalytic reduction/oxidation of pollutants on CP based electrodes, and adsorption of pollutants) and finally electroanalysis as chemical sensors in solution, gas phase, and chiral molecules. This review is expected to be comprehensive, authoritative, and useful to the chemical community interested in CPs and their applications.

Hybrid halide perovskites that are currently intensively studied for photovoltaic applications, also present outstanding properties for light emission. Here, we report on the preparation of bright solid state light emitting diodes (LEDs) based on a solution-processed hybrid lead halide perovskite (Pe). In particular, we have utilized the perovskite generally described with the formula CH 3 NH 3 PbI 3-x Cl x and exploited a configuration without electron or hole blocking layer in addition to the injecting layers. Compact TiO 2 and Spiro-OMeTAD were used as electron and hole injecting layers, respectively. We have demonstrated a bright combined visible-infrared radiance of 7.1 W• sr −1 •m −2 at a current density of 232 mA•cm −2 , and a maximum external quantum efficiency (EQE) of 0.48%. The devices prepared surpass the EQE values achieved in previous reports, considering devices with just an injecting layer without any additional blocking layer. Significantly, the maximum EQE value of our devices is obtained at applied voltages as low as 2 V, with a turn-on voltage as low as the Pe band gap (V turn-on = 1.45 ± 0.06 V). This outstanding performance, despite the simplicity of the approach, highlights the enormous potentiality of Pe-LEDs. In addition, we present a stability study of unsealed Pe-LEDs, which demonstrates a dramatic influence of the measurement atmosphere on the performance of the devices. The decrease of the electroluminescence (EL) under continuous operation can be attributed to an increase of the nonradiative recombination pathways, rather than a degradation of the perovskite material itself.

The effect of semiconductor passivation on quantum-dot-sensitized solar cells (QDSCs) has been systematically characterized for CdS and CdS/ZnS. We have found that passivation strongly depends on the passivation agent, obtaining an enhancement of the solar cell efficiency for compounds containing amine and thiol groups and, in contrast, a decrease in performance for passivating agents with acid groups. Passivation can induce a change in the position of TiO 2 conduction band and also in the recombination rate and nature, reflected in a change in the β parameter. Especially interesting is the finding that β, and consequently the fill factor can be increased with the passivation treatment. Applying this strategy, record cells of 4.65% efficiency for PbS-based QDSCs have been produced. SECTION: Energy Conversion and Storage; Energy and Charge Transport I n the past few years, the interest in the use of light-absorbing inorganic semiconductor materials for nanostructured photovoltaic devices has increased enormously, in particular, in the case of semiconductor quantum dots (QDs), when the semiconductor particle size is smaller than its Bohr radius and quantum confinement regime is attained. 1−7 These materials are extremely interesting for the development of photovoltaic applications for several reasons: tunable band gap, high extinction coefficient, large intrinsic dipole moment, and easy and cheap production.

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The synthesis of fullerenol with various degrees of hydroxylation and the use of a low hydroxylated product to form stable Langmuir films are reported in this work, along with the optical and electrical properties of Langmuir-Blodgett (LB) films obtained on glass and polyaniline (PANI) substrates. The data suggest that an average of 9-12 hydroxyl groups are bound preferentially on one side of the C 60 cage and this allows the formation of stable two-layer films at the air/water interface. The large anisotropy of the hydroxylated molecule provides organized LB films of the type substrate-(D-C 60 -D-C 60 -) n , with D representing the hydroxyl groups. The electrical conductivity of LB films deposited on glass is equivalent to that reported for highly conductive polymeric C 60 but several orders of magnitude higher than that for disordered fullerenol pellets. UV-vis absorptions provide evidence that fullerenol layers cause the deprotonation of PANI, rendering a polymer with low conductivity. The loss of conductivity disagrees with the behavior expected for a donor (PANI)/acceptor (fullerenol) interface, even though current-voltage (I-V) curves of fullerenol LB /PANI junctions indicate some degree of electrical rectification. Additionally, transients observed at large bias on the I-V curves agree with the reported proton conductivity of fullerenol.

Appropriate selection of electron buffer layer and understanding its impact on the photo‐generated charge transfer dynamics at the interfaces are critical to enhance the efficiency of solar cells. By optimizing a multilayer electron buffer composed of CdS thin film deposited on TiO2 compact layer, we obtained a power conversion efficiency (PCE) of 5.47% for a planar solar cell of Sb2(SxSe1‐x)3 absorber. The PCE was significantly enhanced in the photovoltaic parameters of planar solar cells fabricated with single‐layer configuration: for example, PCE of 3.99% and 0.79% were obtained when either CdS or TiO2, respectively, were used. Surface photovoltage spectroscopy, transient photovoltage, and electrochemical impedance spectroscopy analyses indicated that the PCE improvement can be ascribed to a combination of 2 factors: (i) better separation and transfer of the photo‐excited free charge, provided by the beneficial energy level alignment between TiO2 and CdS layers, and (ii) sulfur passivation upon incorporation of CdS in a multilayer configuration causing a reduction in the trap states at the interface with Sb2(SxSe1‐x)3.

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