Synthesis, optical and photovoltaic properties, and Hirshfeld surface analysis of hybrid organic-inorganic 2C6CoCl4

Bulk heterojunction organic solar cell based on liquid crystal semiconducting polymers of poly[9,9-dioctylfluorene-co-bithiophene] (F8T2) as p-type semiconductors and fullerenes (C60) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as electron donor and acceptor has been fabricated and characterized for improving photovoltaic and optical properties. The photovoltaic performance including current voltage curves in the dark and illumination of the F8T2/C60 conventional and inverted bulk heterojunction solar cells were investigated. Relationship between the photovoltaic properties and morphological behavior was focused on tuning for optimization of photo-voltaic performance under annealing condition near glass transition temperature. Additive-effect of diiodooctane (DIO) and poly(3-hexylthiophene-2,5-diyl) (P3HT) on the photovoltaic performance and optical properties was investigated. Mechanism of the photovoltaic properties of the conventional and inverted solar cells will be discussed by the experimental results.

Conventional and inverted organic solar cells of poly[9,9-dioctyl-fluorene-co-bithiophene] (F8T2) as liquid-crystal semiconducting polymer and fullerene as electron acceptor were fabricated and characterized. An effect of thermal treatment of the films on annealing condition near glass transition was investigated for tuning optimization and improving the photovoltaic and optical properties. Annealing treatment below the glass transition improved the photovoltaic performance and carrier diffusion in crystal growth of active layer. The X-ray diffraction patterns indicate a crystalline structure with molecular order of F8T2 in crystal index, 100 as a layer distance between sheets of F8T2 chains. The photovoltaic properties were based on molecular interactions with molecular ordering in active layer at crystal state. As the photovoltaic mechanisms, the F8T2 thin film as p-type semiconducting polymer worked for electron-donor layer to support light-induced generation, carrier diffusion and charge transfer near interface in active layer. Copyright © 2014 John Wiley & Sons, Ltd.

Three heterocyclic dyes were synthesized having in mind the changes in the photovoltaic, optical and redox properties by functionalization of 5-aryl-thieno[3,2-b]thiophene, 5-arylthiophene and bis-methylpyrrolylthiophene π-bridges with different donor, acceptor/anchoring groups. Knoevenagel condensation of the aldehyde precursors with 2-cyanoacetic acid was used to prepare the donor-acceptor functionalized heterocyclic molecules. These organic metal-free dyes are constituted by thieno[3,2-b]thiophene, arylthiophene, bis-methylpyrrolylthiophene, spacers and one or two cyanoacetic acid acceptor groups and different electron donor groups (alkoxyl, and pyrrole electron-rich heterocycle). The evaluation of the redox, optical and photovoltaic properties of these compounds indicate that 5-aryl-thieno[3,2-b]thiophene-based dye functionalized with an ethoxyl electron donor and a cyanoacetic acid electron acceptor group/anchoring moiety displays as sensitizer for DSSCs the best conversion efficiency (2.21%). It is mainly assigned to the higher molar extinction coefficient, long π-conjugation of the heterocyclic system, higher oxidation potential and strong electron donating capacity of the ethoxyl group compared to the pirrolyl moiety.

Bismuth ferrite ceramic powders (BiFeO3) were synthesized by a combustion reaction in solution, using the mixture of urea and glycine as fuels, whose objectives were to improve their optical, electrical and photovoltaic response properties. X-ray diffraction analysis indicated the formation of the single phase BiFeO3. Transmission electron microscopy (TEM) shows images of uniform nanoparticles of 70 nm on average. Through diffuse reflectance we obtain a band gap with a direct electronic transition of 2.14 eV, this value presents an improvement compared to that reported by other authors in BiFeO3 ceramic powders. The value of the resistivity obtained by the 4-pointed method was ρ = 0.486 × 106 Ω.cm, checking that our material is a semiconductor. Finally, by building a prototype of Ag/BiFeO3/Ag, with visible light (λ = 405 nm), a photovoltaic response of 0.2 nA at room temperature was achieved.

In this study, the synthesis of 4 new heterocyclic compounds derived from quinoxalinedione were presented, which have been characterized by 1H and 13C NMR spectroscopy. The solar cells’ photovoltaic properties based on these novels organic compounds donor-π-acceptor dyes were studied. Density functional theory DFT method is realized to optimize electronic parameters, optical and photovoltaic properties for some new 8-hydroxyquinoline derivatives based on quinoxaline-2,3-dione. The results have shown that time-dependent DFT (TDDFT) investigations with polarizable continuum model PCM were significantly able to foretell the excitation energy and the spectroscopy of the molecule. The highest occupied molecular orbital HOMO and the lowest unoccupied molecular orbital LUMO energy levels of these molecules can ensure a positive impact on the dye regeneration and electron injection process. Injection driving force ΔGinject, light-harvesting efficiency LHE, reorganization energy λtotal and open-circuit photovoltage Voc provide qualitative predictions on these dyes’ reactivity. Among these 4 molecules, the compounds which can be used as organic solar cells have determined.
 HIGHLIGHTS
 
 We presented the synthesis and the characterization of a new series of heterocyclic compounds obtained by association of 8-hydroxyquinoline with quinoxalindione derivatives.
 The synthesis of this series of compounds was carried out by simple conditions but with good yields and the characterization data shows that there is good consistency between the spectroscopic data and the proposed structures
 These new compounds were obtained according to simple procedures with good yields and they have been the subject of a theoretical study
 This investigated process can be employed to predict the optical and photovoltaics properties on the other compounds and polymers, and it encourages to synthesis the novel organic solar cell materials
 
 GRAPHICAL ABSTRACT

Boron-doping effect on the super-high density Si quantum dot thin films utilizing a gradient Si-rich oxide multilayer structure

Novel benzo[f]quinoxalino[2,3-β]porphyrin carboxylic acid (ZnBQA) and cyanoquinoxalino[6,7-β]porphyrin carboxylic acid (ZnQCA) have been synthesized to evaluate the effects of the π-elongation and the fused position of quinoxaline-fused porphyrins on the optical, electrochemical, and photovoltaic properties. ZnBQA showed a split, red-shifted Soret band relative to that of quinoxalino[2,3-β]porphyrin acid (ZnQMA), while the Q bands are rather blue-shifted. On the other hand, both Soret and Q-bands of ZnQCA are red-shifted compared to those of ZnQMA. The optical HOMO−LUMO gaps are consistent with those estimated by density functional theory calculations. The photovoltaic properties were compared under the optimized conditions in which a sealed device structure with TiCl4-treated, TiO2 double layers was used. The ZnBQA cell exhibited a relatively high power conversion efficiency (η) of 5.1%, while the ZnQCA cell yielded a low η value of 0.80%. Both of the η values are smaller than those of reference cells un...

Optical, electrical and photovoltaic properties of thermally evaporated 3-amino-2-[(2-nitrophenyl)diazinyl]-3-(piperidin-1-yl)acrylonitrile thin films

In hybrid perovskites, MAPbI3 and MAPbBr3 have been extensively studied for their optical and photovoltaic properties, but MAPbCl3 is significantly less investigated for its optical and photovoltaic properties due to its low photoluminescence quantum yield (PL QY) and a largeband gap. However, the large band gap makes it a suitable host for doping transition metal ions to explore new optical properties. We synthesized nanocrystals (NCs) of MAPbCl3 doped with Mn2+ by simple ligand assisted reprecipitation method. The reaction temperature and Pb to Mn feed ratio were optimized by preparing a series of Mn2+-doped MAPbCl3 NCs. The prepared NCs show bright Mn2+ emission with ~13% PL QY suggesting an efficient energy transfer from host NCs to Mn2+. Since the large bandgap of MAPbCl3 precludes the possibility of investigating temperature dependent PL and lifetime measurements to understand the excited state dynamics, we carried out these experiments on Mn2+ doped MAPbCl2.7Br0.3 with the Br concentration adjusted to bring the bandgap of the alloyed system within the limits of the experimental technique. Our studies establish an anomalous behavior of Mn2+ PL emission in this host. These results reveal the origin of a temperature mediated energy transfer from exciton to Mn2+ and provides an understanding of the underlying mechanisms of PL properties of this new class of NCs.

Non-fused-ring asymmetrical electron acceptors assembled by multi-functional alkoxy indenothiophene unit to construct efficient organic solar cells

A series of [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM)‐like fullerene derivatives with the butyl chain in PCBM changing from 3 to 7 carbon atoms, respectively (F1–F5), are designed and synthesized to investigate the relationship between photovoltaic properties and the molecular structure of fullerene derivative acceptors. F2 with a butyl chain is PCBM itself for comparison. Electrochemical, optical, electron mobility, morphology, and photovoltaic properties of the molecules are characterized, and the effect of the alkyl chain length on their properties is investigated. Although there is little difference in the absorption spectra and LUMO energy levels of F1–F5, an interesting effect of the alkyl chain length on the photovoltaic properties is observed. For the polymer solar cells (PSCs) based on P3HT as donor and F1–F5, respectively, as acceptors, the photovoltaic behavior of the P3HT/F1 and P3HT/F4 systems are similar to or a little better than that of the P3HT/PCBM device with power conversion efficiencies (PCEs) above 3.5%, while the performances of P3HT/F3 and P3HT/F5‐based solar cells are poorer, with PCE values below 3.0%. The phenomenon is explained by the effect of the alkyl chain length on the absorption spectra, fluorescence quenching degree, electron mobility, and morphology of the P3HT/F1–F5 (1:1, w/w) blend films.

ABSTRACTNew donor–π–acceptor organic (D–π–A) dyes composed of triarylamine, oligothiophene, and phosphole subunits were prepared, and their optical and photovoltaic properties were investigated. The regioselective α‐lithiation of the thiophene ring of 2‐(thiophen‐2‐yl)phospholes bearing an ester group, followed by treatment with tributyltin chloride afforded 2‐(5‐(tributylstannyl)thiophen‐2‐yl)phosphole derivatives, which underwent Stille coupling with 5′‐(p‐(diarylamino)phenyl)‐5‐bromo‐2,2′‐bithiophene to give triarylamine–terthiophene–phosphole hybrid π systems bearing the terminal ester group. The alkaline hydrolysis of the ester group yielded the target dyes, bearing the carboxylic acid anchoring group. The UV–vis absorption spectra of the new N,S,P‐hybrid dyes displayed broad and intense π–π* transitions with two absorption maxima in the visible region. Density functional theory (DFT) calculations of two dye models revealed that each highest occupied molecular orbital (HOMO) resides on the triarylamine–oligothiophene π network, whereas each lowest unoccupied molecular orbital (LUMO) is basically located on the phosphole subunit. In addition, the time‐dependent DFT calculations of the models showed that the lowest energy bands of these hybrid dyes are mainly consisted of the HOMO‐to‐LUMO+1 and HOMO‐to‐LUMO transitions with the large intramolecular charge‐transfer character. The N,S,P‐hybrid‐dye‐sensitized TiO2 cells exhibited moderate power conversion efficiencies of up to 5.6%. The present findings corroborate the potential utility of the phosphole skeletons as the acceptor components in the D–π–A sensitizers.

An overview of metal-free diazine-based dyes for dye-sensitized solar cells: Synthesis, optical, and photovoltaic properties

Growth, properties and dye-sensitized solar cells–applications of ZnO nanorods grown by low-temperature solution process

The aim of this work is to search for new molecules with a photovoltaic performance for use in the field of organic solar cells. To achieve this goal, starting from a series of D–A–D bis-dipolar emissive oligoarylfluorenes and derivatives, the acceptor unit (A) is replaced by other different acceptors to improve their electronic optical and photovoltaic properties. The calculations were done using the B3LYP method with the base 6-31G(d,p) to optimize the geometry of the studied molecules and to determine the energies of HOMO, LUMO and band Gap. On the other hand, in order to study the electronic excitation spectra, the TD-B3LYP/6-31G (d,p) were used to calculate the absorption properties (λmax, OS). The results show that the designed molecules proposed here exhibit better performances including lower HOMO energy, a larger absorption range and better theoretical open circuit voltage (VOC). These compounds can be used as potential electron donors in organic solar cells Hetero-junction (BHJ), thanks to their better electronic and optical properties and good photovoltaic PV.