The partial Pb2+ substitution with Cu+ ions has been thoroughly applied as an approach to produce new absorber materials with enhanced light and radiation hardness required for potential aerospace applications of perovskite solar cells. X-ray photoelectron spectroscopy revealed that Cu+ ions are partially integrated into the crystal lattice of MAPbI3 on the surface of perovskite grains and induce p-doping effect, which is crucial for a range of applications. Importantly, the presence of Cu+ enhances photostability of perovskite films and blocks the formation of metallic lead as a photolysis product. Furthermore, we have carried out one of the first studies on the radiation hardness of complex lead halides exposed to two different stressors: gamma-rays and 8.5 MeV electron beams. The obtained results demonstrate that Cu+ doping alters completely the radiation-induced degradation pathways of the double cation perovskite. Indeed, while Cs0.12FA0.88PbI3 degrades mostly with segregation of delta-phase of FAPbI3 forming a Cs-rich perovskite phase, the Cs0.12FA0.88Pb0.99Cu0.01I2.99 films tend to expel delta-CsPbI3 and produce FA-rich perovskite phase, which shows impressive tolerance to both gamma-rays and high energy electrons. The beneficial effect of copper ion incorporation on the stability of lead halide perovskite solar cells under light soaking and gamma-ray irradiation conditions has been shown. The discovered possibility of controlling the electronic properties and major materials degradation pathways through minor modification of their chemical composition (e.g., replacing 1% of Pb2+ with Cu+) opens up tremendous opportunities for engineering new perovskite absorber compositions with significantly improved properties for both terrestrial and aerospace applications.image

Correction for ‘Experimental evaluation of indium( i ) iodide as a lead-free perovskite-inspired material for photovoltaic applications’ by Marina I. Ustinova et al. , J. Mater. Chem. C , 2022, 10 , 3435–3439, https://doi.org/10.1039/D1TC05583F.

Rare earth metal oxides (REOs) represent promising gate dielectric materials for field-effect transistors due to their high dielectric constants required for suppressing leakage currents in devices. In this paper, we present an approach to deposition of uniform REO gate dielectric coatings by oxidation of thin rare earth metal films in air at relatively low temperatures (100-250 degrees C). The proposed methodology was extensively explored in organic field-effect transistors (OFETs) using five benchmark organic semiconductors and six REOs as gate dielectrics. It was shown that OFETs with the REO gate dielectrics deliver on average considerably better characteristics compared to the reference devices using electrochemically grown aluminum oxide dielectric (AlOx). OFETs on a flexible plastic substrate were demonstrated, which makes this approach very attractive for developing flexible and wearable electronic devices with improved performance.

A new BODIPY-coumarin dye was synthesized, characterized, and utilized as a light-sensitive component in optically programmed OFET-based memory cells and photodetectors.

Low structural dimensionality and the anisotropy of carrier transport in In I films are the main reasons why they show modest performances in solar cells (PCE = 1%) but demonstrate high photodetectivity (>103) in lateral photodetectors.

A low bandgap conjugated polymer comprising benzodithiophene and diketopyrmlopyrrole units was designed and synthesized. The polymer showed an optical bandgap of similar to 1.3 eV and exhibited broad absorption in visible and near-infrared spectral ranges. Photodetectors based on the polymer/fullerene derivative blends were fabricated and their electrical behavior was investigated. The devices demonstrated rapid response in the infrared (lambda = 850 nm) wavelengths. Photodetectors can be operated in up to 2.6 x 10(5) Hz frequency regime with responsivity of 42 mA W-1 and detectivity of 1.26 x 10(12) Jones at lambda = 850 nm and zero external bias.

Push-pull type conjugated oligomer TBTBT with alternating thiophene (T) and benzothiadiazole (B) blocks was studied as an electron transport layer (ETL) material for p-i-n perovskite solar cells. The devices assembled using TBTBT as the single-component ETL provided the encouraging photovoltaic performance as reflected in the obtained power conversion efficiency (PCE) of 14.3%. The hybrid ETL structure composed of PC61BM/TBTBT bilayer increased substantially the device short circuit current density and boosted PCE from 14.3% to 17.4%. Even though the application of TBTBT as the component of hybrid ETL did not enhance the device efficiency as compared to the reference cells using PC61BM, such modification significantly improved the operational stability of PSCs, which is crucially important for practical implementation of this technology.

Herein, we reveal for the first time a comprehensive mechanism of poorly investigated electrochemical decomposition of CH3NH3PbI3 using a set of microscopy techniques (optical, AFM, PL) and ToF-SIMS. We demonstrate that applied electric bias induces the oxidation of I- to I-2, which remains trapped in the film in the form of polyiodides, and hence, the process can be conceivably reversed by reduction. On the contrary, reduction of organic methylammonium cation produces volatile products, which leave the film and thus make the degradation irreversible. Our results lead to a paradigm change when considering design principles for improving the stability of complex lead halide materials as those featuring organic cations rather than halide anions as the most electric field-sensitive components. Suppressing the electrochemical degradation of complex lead halides represents a crucial challenge, which should be addressed in order to bring the operational stability of perovskite photovoltaics to commercially interesting benchmarks.

We explored the radiation stability of carbazole-based electron-donor conjugated polymers, acceptor fullerene derivative [60]PCBM, and their blends as active layer components of organic solar cells. An exposure to γ rays induced evident degradation effects in bulk samples of the pristine fullerene acceptor ([60]PCBM) and two investigated electron-donor conjugated polymers: PCDTBT and PCDTTBTBTT. The most severe radiation damage occurred in [60]PCBM as can be concluded from the significant losses in open circuit voltage, fill factor, and efficiency of photovoltaic (PV) devices comprising the exposed fullerene acceptor. Conjugated polymers PCDTBT and PCDTTBTBTT showed substantially different radiation stabilities: the samples of PCDTTBTBTT exposed to 200 Gy lost ∼25% of their nominal photovoltaic efficiency due to a substantial decay of all device parameters, while PCDTBT alone showed just a minor aging under the same conditions. The fullerene-polymer composites were much more resistant with respect to the radiation damage than the bulk samples of pristine materials. In particular, the PCDTBT/[60]PCBM composite films demonstrated an outstanding radiation stability while maintaining more than 80% of the initial photovoltaic efficiency after exposure to γ rays with a maximum absorbed dose of 6500 Gy. Considering an average annual radiation dose of 160 Gy according to the NASA estimations for satellites at geocentric Earth orbits, organic solar cells based on PCDTBT/[60]PCBM blends hold a promise to deliver lifetimes well above 10 years. The revealed impressive radiation stability of PCDTBT/[60]PCBM blends in combination with other advantages of organic solar cells, for example, their mechanical flexibility and lightweight, points to a bright future of this PV technology in space industry applications.

Here we report the application of the Electron Spin Resonance (ESR) spectroscopy as a highly sensitive analytical technique for assessment of the electronic quality of organic semiconductor materials, particularly conjugated polymers. It has been shown that different batches of the same conjugated polymer might contain substantially different amounts of radical species which were attributed to structural defects and/or impurities behaving as traps for mobile charge carriers. Good correlations between the concentrations of radicals in various batches of conjugated polymers and their performances in organic solar cells have been revealed.

It was shown that ESR spectroscopy is a very useful technique for monitoring the photochemical and thermal degradation of conjugated polymers commonly used in organic solar cells. The relative stability of materials can be quantified by comparing the rates of trap accumulation (dC(R)/dt) estimated from their ESR profiles.

Highly soluble fullerene derivatives (HSFD) and a low soluble polymer (LSP) were investigated as modifiers of the active layer morphology in conventional P3HT/PCBM bulk heterojunction solar cells. The observed changes in photovoltaic and electrical characteristics of the devices after addition of one or two modifiers suggest that they induced favourable vertical phase separation in the blends simply due to different solubilities of the components. In particular, HSFD is supposed to accumulate at the top of the film serving as a hole-blocking interlayer at the cathode/active layer interface. On the contrary, LSP seems to form electron-blocking buffer layer at the bottom of the device at the active layer/anode interface. Thus, the differential material solubility was suggested as a tool for adjustment of vertical morphology of organic bulk heterojunction solar cells.

The problem of batch‐to‐batch variation of electronic properties and purity of conjugated polymers used as electron donor and photon harvesting materials in organic solar cells is addressed. A simple method is developed for rapid analysis of electronic quality of polymer‐based materials. It is shown that appearance of impurities capable of charge trapping changes electrophysical properties of conjugated polymers. In particular, a clear correlation between the effective relaxation time τ eff and relative photovoltaic performance ( η / η max ) is revealed for samples of poly(3‐hexylthiophene) intentionally polluted with a palladium catalyst. This dependence is also valid for all other investigated samples of conjugated polymers. Therefore, fast impedance measurements at three different frequencies allow one to draw conclusions about the purity of the analyzed polymer sample and even estimate its photovoltaic performance. The developed method might find extensive applications as a simple tool for product quality control in the laboratory and industrial‐scale production of conjugated polymers for electronic applications.

Novel perylene diimide Py-PDI and naphthalene diimide Py-NDI possessing chelating pyridyl groups have been synthesized. The materials are comparatively investigated as electron acceptors in small molecular photovoltaic cells comprising zinc phthalocyanine ZnPc as an electron donor component. It was shown that these compounds form self-assembled coordination complexes with ZnPc in solution and co-evaporated solid blends. Py-PDI and Py-NDI used as electron acceptor materials in photovoltaic cells with donor ZnPc significantly outperform the reference materials, i.e. perylene and naphthalene diimides that possess no chelating pyridyl groups. Superior photovoltaic performance of Py-PDI and Py-NDI is explained by a complex formation between these compounds and ZnPc. Such interactions of donor and acceptor materials strongly improve photoinduced charge carrier generation. This gives great advantages not just for the construction of organic solar cells but also for organic photodetectors. The devices fabricated in this study are also useful as fast and highly sensitive photodetectors with response times of less than 10 microseconds as well as a strong photoconductive behavior under forward bias.