The Effect of Fullerene Derivatives Ratio on P3HT-based Organic Solar Cells

The effect of fullerene ratio PCBM and ICBA on the P3HT-based solar cells were investigated under ambient conditions; the ratio was varied in the range of 1-3. The optical, morphological, structural, and electrical characteristics were investigated both in dark and under illumination. The absorption spectra have revealed a decrease in the intensities by increasing the fullerene ratio and the peaks were blue shifted. Moreover, florescence spectra demonstrated charge transfer from P3HT to fullerene molecules due to uniform distribution of fullerene domains within the P3HT matrix. XRD patterns have shown a strong reduction in the crystallinity by increasing the ratio of fullerene within the blend. Furthermore, AFM images showed smother surface corresponding to pinholes with higher ratio while rougher surface with lower fullerene ratio was observed. The best performance was recorded for P3HT:PCBM (3:1) with VOC = 0.58 volt, JSC = 9.9 mA.cm-2 and PCE 1.82%. The fill factor (FF) was found to be small for all studied samples which could be associated with the preparation conditions where all samples were prepared under normal ambient. Devices which demonstrated best performance were attributed to improved crystallinity and enhanced light absorption of the active layer

Metal salt modified PEDOT : PSS as anode buffer layer and its effect on power conversion efficiency of organic solar cells

The effects of metal chlorides such as LiCl, NaCl, CdCl2 and CuCl2 on optical transmittance, electrical conductivity as well as morphology of PEDOT:PSS films have been investigated. Transmittance spectra of spun PEDOT:PSS layers were improved by more than 6 to a maximum of 94 in LiCl doped PEDOT:PSS film. The surface of the PEDOT:PSS films has exhibited higher roughness associated with an increase in the electrical conductivity after doping with metal salts. The improvement in the physical properties of PEDOT:PSS as the hole transport layer proved to be key factors towards enhancing the P3HT:PCBM bulk heterojunction (BHJ) solar cells. These improvements include significantly improved power conversion efficiency with values as high as 6.82 associated with high fill factor (61) and larger short circuit current density (�18 mA cm-2). Keywords: Chlorine compounds; Conversion efficiency; Electric conductivity; Electrodes; Heterojunctions; Metals; Semiconductor doping; Solar cells, Electrode modification; Metal salt; Organic solar cell; P3HT:PCBM; PEDOT:PSS, Conducting polymer

Understanding the gas adsorption kinetics of Langmuir-Schaefer porphyrin films using two comparative sensing systems

This study investigated Langmuir-Schaefer (LS) films of a free base porphyrin 5,10,15,20-tetrakis[3,4-bis(2-ethylhexyloxy)phenyl]-21H,23H-porphine (EHO) as sensors to detect acetic acid and methylamine. Such films are known to adsorb VOCs, resulting in a color change and a swelling of the film resulting in a thickness increase for the film. The adsorption kinetics of this process were studied using two different techniques, namely UV–vis absorbance spectroscopy and surface plasmon resonance (SPR), to investigate the color change and film thickness change respectively when exposed to acetic acid and methylamine vapors. These two techniques were used to allow a comparative study to be made of the color change and film swelling in order to enhance understanding of the interaction between the thin films and both acidic and basic vapor molecules. The transfer process of the LS thin films was performed using the constant transfer pressure of 5 mNm−1. EHO films with different numbers of layers were fabricated and exposed to 855 ppm acetic acid and 900 ppm methylamine vapor. Sensor responses were recorded using both UV–vis and surface plasmon resonance techniques. The EHO films exhibited high sensitivity and fast responses using both techniques. Using two different detection systems permitted the investigation of the interaction mechanism with a quantitative, comparative study with the aim of obtaining an enhanced understanding of the nature of the interaction of the organic vapors with the sensor. The interaction between EHO and the analytes can be considered in terms of three processes which are surface adsorption, diffusion and desorption process. Although both the optical techniques have distinct sensing principles, similar vapor interaction characteristics can be distinguished in both sets of experiments. For both techniques the response to the acid was stronger than the response to methylamine. However, apart from this difference in the magnitude of the responses the interaction with the acid and base were remarkably similar. The sensitivity of the sensor is largely independent of the measurement system

Chemistry of gold(I, III) complexes with organic ligands as potential MOCVD precursors for fabrication of thin metallic films and nanoparticles

The present review deals with the chemistry of complexes of gold(I) and gold(III) with organic ligands. Compounds classified according to the type of coordinating ligands and donor atoms are considered from the point of view of their potential application as precursors in the MOCVD process, which attract considerable scientific interest. This method has undeniable advantages over other technologies (precision multi-parameter monitoring in order to control the properties of the obtained coatings, high utilization of precursors, simple equipment design, etc.) and can be used to produce thin films and gold nanoparticles with desired characteristics on different types of surfaces of complex geometries for various engineering applications. The following main results published to date are summarized and analyzed in this review: (a) chemical approaches to synthesis, structural characteristics and properties of the main classes of organic compounds of gold (I, III), (b) thermal stability of gold compounds in solid state, (c) temperature-dependent measurements of vapor pressure used for the characterization of gold compound volatility, (d) thermolysis processes of gold complex vapor on heated substrates, (е) examples of modern high-precision applications of gold precursors in MOCVD technique of metallic layers and nanoparticles. Mechanisms and growth processes of gold films and nanoparticles, their composition, structure, and characteristics are also considered

Highly reproducible perovskite solar cells via controlling the morphologies of the perovskite thin films by the solution-processed two-step method

Organic-inorganic halide perovskites are one of the most attractive materials for the next generation solar cells. The PCE has rapidly increased to more than 22% using different configurations and techniques and further developments are predicted. However, perovskite solar cells suffer from fabrication reproducibility mainly due to difficulty in controlling the morphology of the perovskite films themselves. In this paper we present a low temperature solution-processed two-step deposition method to fabricate CH3NH3PbI3 perovskites. This method offers a simple route with great potential in fabricating reproducible perovskite solar cells. In the present work, we demonstrate that the morphology of the perovskite thin films is highly determined by the concentration of Methylammonium iodide (MAI) as well as the reaction time between MAI and PbI2. High-performance solar cells have been reproducibly achieved with a highest PCE of 15.01% for PCBM-based planar heterojunction solar cells

Laser Ablation in Different Environments and Generation of Nanoparticles

In the last two decades, pulsed-laser ablation has received attention from researchers in micro- and nanotechnology. During the development of laser ablation in materials processing, several media, such as vacuum, air, gases and liquids, have been used to improve the quality and quantity of laser machining and production of nanoparticles. The laser-ablation environment is important in order to control the average size and chemical compositions of nanoparticles. Conducting the laser-ablation process in liquid environments has become of increasing relevance for the production of precise and pure micromachining and nanomaterials. In addition, deionised water has been found to be the optimal environment to produce nanoparticles for bioapplications

Rutile TiO2 films as electron transport layer in inverted organic solar cell

Titanium dioxide (TiO2) thin films were prepared by sol–gel spin coating method and deposited on ITO-coated glass substrates. The effects of different heat treatment annealing temperatures on the phase composition of TiO2 films and its effect on the optical band gap, morphological, structural as well as using these layers in P3HT:PCBM-based organic solar cell were examined. The results show the presence of rutile phases in the TiO2 films which were heat-treated for 2 h at different temperatures (200, 300, 400, 500 and 600 °C). The optical properties of the TiO2 films have altered by temperature with a slight decrease in the transmittance intensity in the visible region with increasing the temperature. The optical band gap values were found to be in the range of 3.28–3.59 eV for the forbidden direct electronic transition and 3.40–3.79 eV for the allowed direct transition. TiO2 layers were used as electron transport layer in inverted organic solar cells and resulted in a power conversion efficiency of 1.59% with short circuit current density of 6.64 mA cm−2 for TiO2 layer heat-treated at 600 °C

Study the effect of acid immersion on the hardness of (Epoxy – Granite) composite

This work has been done with using of epoxy resin mixed with Granite powder were weighted by percent volume (5,10,15, and 20)%and then mixed with epoxy polymer to compose polymer composite. Hand lay-up technique is used in fabrication of the composite samples. Hardness test was carried out for the proper samples in both normal condition and after immersion in HCL (1 M and 2 M) solutions for periods ranging up to 10 weeks. After comparing the results between the polymer and their composite, the hardness increased with increasing Granite weight percent, it was found that Hardness were greater for the composites before immersion compared with their values after immersion