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High-efficiency dye-sensitized solar cells using ferrocene-based electrolytes and natural photosensitizers

A new and promising dye-sensitized solar cell (DSSC) bilayer design was developed using an Fe2+/Fe3+ (ferrocene) liquid electrolyte and natural dyes extracted from Hypericum perforatum, Rubia tinctorum L. and Reseda luteola. The photovoltaic parameters controlling the device performance were then investigated. A DSSC based on quercetin dye displayed the most efficient solar to electricity conversion efficiency compared with other dyes with a maximum η value of 2.17%. Maximum overall conversion efficiencies under simulated sunlight that was comparable to natural photosynthesis were increased by 15%. The identification of appropriate additives for improving VOC without causing dye degradation may result in further enhancement of cell performance, making the practical application of such systems more suitable for achieving economically viable solar energy devices.

Investigation of the photoinduced electron injection processes for natural dye-sensitized solar cells: the impact of anchoring groups

In this study, nine different natural dyes having various anchoring groups were extracted from various plants and used as photo-sensitizers in DSSC applications. The photovoltaic parameters controlling the cell performance were investigated and the results were discussed as a function of anchoring groups. The obtained power conversion efficiencies (PCEs) vary from 0.18 to 1.87%, while the quantum yields are heavily dependent on both the anchoring group and type of pigments. Moreover, the effects of anchoring groups on the photoinduced electron injection dynamics from natural dye molecules to TiO2 nanoparticles were studied using time resolved fluorescence spectroscopy measurements. In these dyes, the long-hydroxyl & carbonyl-chain bearing anthocyanin, with the maximum electron transfer rate (kET), has shown the best photosensitization effect with regard to cell output. Despite the fact that their performance in DSSCs is somewhat lower or close to the metal complexes, these metal-free natural dyes can be treated as a new generation of sensitizers.

Polyaniline micro-rods based heterojunction solar cell: Structural and photovoltaic properties

The present paper reports the fabrication and photovoltaic characterization of pure and dodecyl benzene sulfonic acid (DBSA)-doped polyaniline (PAni) micro-rods polymer/n-Si heterojunction solar cells, and also the morphological and structural properties of pure and micro-rods PAni doping with DBSA. The device shows a strong photovoltaic behavior with a maximum open-circuit voltage Voc of 0.83 V, a short-circuit current Jsc of 14.72 mA cm−2, fill factor FF of 0.54 resulting in an estimated device efficiency η of 6.13% under simulated solar light with the intensity of 100 mW/cm2. The results indicate that the Au/DBSA-doped PAni micro-rods/n-Si heterojunction structure might be promising for the solar cell applications.

Improvement in electrical performance of half-metallic Fe3O4/GaAs structures using pyrolyzed polymer film as buffer layer

In this work, the Fe3O4 magnetic nanoparticles (MNPs) were synthesized by a colloidal method. TEM images reveal that Fe3O4 MNPs are spherical in shape with a narrow size distribution in the range of 6–7 nm. These MNPs were used in the fabrication of two types of n-GaAs-based structures: (i) Fe3O4/n-GaAs (reference); and (ii) Fe3O4/PPF/n-GaAs. We present that carbon-based pyrolyzed polymer films (PPFs), as a buffer layer, can control the electrical characteristics of a conventional Fe3O4/n-GaAs device. The behaviour of the apparent barrier height and ideality factor with the interfacial layer due to the presence of the interface state density is discussed. PPF raises the barrier height in a Fe3O4/PPF/n-GaAs half-metallic/insulator/semiconductor (h-MIS) device as high as 0.62 0.002 eV. Furthermore, Fe3O4/PPF interfaces exhibit unique electronic properties including high-quality interface, low series resistance (from 17.73 kΩ to 85.66 Ω) and extremely low interface state density (1.76 × 1012 eV−1 cm−2). Compared to the electrical performance for the Fe3O4/n-GaAs junction, that for the Fe3O4/PPF/n-GaAs junction was enhanced.

Hydrothermally processed CuCrO2 nanoparticles as an inorganic hole transporting material for low-cost perovskite solar cells with superior stability

Despite the impressive photovoltaic performances of perovskite solar cells (PSCs) with a power conversion efficiency (PCE) beyond 22%, intensive studies are still required to overcome ongoing issues such as cost, stability, and hysteresis. Here, for the first time, we report a cesium-containing triple-cation mixed-halide perovskite solar cell (n–i–p structure) by using hydrothermally synthesized inorganic CuCrO2 (CCO) delafossite nanoparticles as a hole transporting material (HTM). After optimization of the concentration, a fully homogeneous and completely covered CCO layer that facilitates fast carrier extraction and collection was obtained on the surface of the perovskite. Our CCO-based cells achieved the best PCE of 16.7% (average 16.04 ± 0.40) with negligible hysteresis. More importantly, it was found that our cells showed a significant improvement in stability in ambient air compared with Spiro-OMeTAD HTM-based cells. After 60 days of storage in air without encapsulation, PCE remained at ∼83% of the initial value with the CCO-based cells, whereas it decreased to ∼24% of the initial value with devices based on the Spiro-OMeTAD HTM. Furthermore, cost estimation results indicated that the current prospect of CCO has an affordable cost/device ratio (∼180-fold cheaper than Spiro-OMeTAD). This work not only reveals the importance of air-stable inorganic HTMs, but also provides a low-cost HTM for highly efficient and stable PSCs.