Ayi Bahtiar

Charge Carrier Dynamics of Active Material Solar Cell P3HT:ZnO Nanoparticles Studied by Muon Spin Relaxation (μSR)

Poly (3-hexylthiohene) (P3HT) has attracted much attention due to their chemical and thermal stability as well as their potential to be used as an active material in solar cells. Recently, hybrid solar cell has been developed due to the combining advantages of organic material (P3HT) and inorganic material such as nanoparticle zinc oxide (ZnO). ZnO is an inorganic material with high electron mobility and easy to prepare as electron acceptor to dissociate excitons formed in conjugated polymer as the active material of solar cells. ZnO also can be prepared as a nanoparticle that can resolve a problem of small exciton diffusion length of P3HT. However, the clearly explanation about the effect of ZnO to the charge carrier dynamics in P3HT is not fully understanding yet. We have studied charge carrier dynamics in active material of solar cell P3HT:ZnO along and perpendicular to the chain by means of longitudinal field (LF) muon-spin-relaxation (μSR) method to elucidate the intra and inter-chain charge carrier in polymer hybrid P3HT:ZnO. We found the charge carrier transport changes from intra-chain to inter-chain diffusion. One dimensional intra-chain diffusion is observed in the samples at low temperatures, while three dimensional inter-chain is observed at high temperatures.

Synthesis and characterization of PVP-capped ZnO particles and its blend with poly(3-hexylthiophene) for hybrid solar cells application

ZnO nanoparticles (ZnO-NPs) agglomeration has been a long main problem on its utilization as acceptor materials of hybrid solar cell using blend of conjugated polymer poly(3-hexylthiophene) or P3HT and ZnO-NPs. Numbers of ZnO nanoparticle agglomeration lead to inhomogeneity of blend film morphology. This agglomeration causes ineffective electron transport within ZnO-NP, and thus lowers power conversion efficiency of hybrid solar cell. In this work, the ZnO particles were capped by PVP (poly-4-vinylpyrrolidone) to reduce agglomeration of ZnO particle and to improve homogeneity of blend P3HTZnO particles film. We used two different type of capping; first capping was applied during the synthesis of ZnO and second the capping was carried out after synthesis of ZnO. The ZnO particles were synthesized using sol-gel method at low temperature (27°C). We have found that the surface morphology of blend films which was ZnO-capped after synthesis is more homogeneous than that of during synthesis.

Preparation of ZnO nanoparticles for blend of P3HT:ZnO nanoparticles:PCBM thin film and its charge carrier dynamics characterization

Recently, many researchers have paid attention to develop active material of solar cell which plays an important role in absorbing solar spectrum. This active material should have an ability to transfer charge carrier resulted from the absorption of solar spectrum. The hybrid organic-inorganic solar cell has been developed due to the combining advantages between organic material Poly(3-hexylthiophene) (P3HT) and fullerene PCBM with inorganic material ZnO nanoparticles. The investigation of charge carrier dynamics in blend P3HT:ZnO nanoparticles:PCBM film as an active material of solar cell devices is an important things to enhance the solar cell performance. The charge carrier dynamics properties is needed to control the morphology of active material to produce an efficient and effective charge dissociation. In this study we synthezed the ZnO nanoparticles by using sol-gel methods. The size of nanoparticles resulted from the reflux process of zinc acetate in methanol by the presence of catalist sodium hyd...

Hybrid solar cells of conjugated polymers metal-oxide nanocrystals blends; state of the art and future research challenges in Indonesia

Ever-increasing world energy demand, depleting non-renewable energy resources and disruptive climate change due to greenhouse gases has aroused much interest in alternative renewable energy sources. Solar energy is one of the best available alternatives, for it is both abundant and clean. Solar cell is an effective device for converting solar energy into electricity. Indonesia is located on the equator where the sunlight is always available in abundance throughout the year; therefore solar cell would become the main source of electrical energy in Indonesia. However, the high cost of inorganic solar cells in spite of their high power conversion efficiency (PCE) has been a major constrain for their mass utilization in Indonesia. The only way to reduce the cost of production and installation is to find other materials which offer low-cost and easy processing into solar cells. Polymer solar cells have been intensively investigated for high performance and low-cost solar cells. Today, 9-11% power conversion efficiency (PCE) of small area polymer solar cells and 2-4% PCE of large area or module solar cells are already achieved. However, for practical application and mass production, 10% or higher PCE of module solar cells is highly required. The main strategic issue for improving the PCE is to use blend of conjugated polymer-metal oxide nanocrystals as active materials for hybrid solar cells, due to the good combination of the versatile solution processability of conjugated polymers and high charge carrier mobility of metal-oxide nanocrystals. In this paper, current development of hybrid solar cells worldwide and future research challenges in Indonesia will be discussed.

The optical band gap investigation of PVP-capped ZnO nanoparticles synthesized by sol-gel method

ZnO Nanoparticles (NPs) has unique natures on their crystal structure, direct band gap and high exciton binding energy, consequently applied in optoelectronic devices such as solar cells, optical wave guide and light emitting diodes (LED). However the drawback was ZnO NPs tend to agglomerate and turn to nano-structured materials with poor properties. Effort to avoid agglomerations generally resolved by surface modification of ZnO NPs to obtain well-dispersed suspension. However changes in the surface of ZnO NPs may change the electronic structure and density of states of ZnO NPs, in turn may change the optical band gap. Thus, the objective of current research is investigation of optical band gap of ZnO NPs due to surface modification by capping agent of poly-4-vinylpyrrolidone (PVP) molecules. Uncapped and PVP-capped ZnO nanoparticles were prepared by sol-gel method. The characteristics of surface modifications were investigated by UV-Vis and Photo Luminescence spectroscopy and Transmission Electron Micro...

Optical, Structural and Morphological Properties of Ternary Thin Film Blend of P3HT:PCBM:ZnO Nanoparticles

Ternary blend film of conjugated polymer, fullerene and inorganic nanoparticles has intensively studied as active material for high power conversion efficiency (PCE) of hybrid organic-inorganic solar cells. The incorporation of two electron acceptor materials of organic fullerene and inorganic nanoparticles into hybrid with electron donor conjugated polymer is strongly believed can improve the PCE of solar cells by increasing exciton dissociation efficiency due to an increase of interface area between donor and acceptor materials where the positive and negative charges dissociated. We studied optical, structural and morphological properties of ternary thin film containing blend of conjugated polymer poly(3-hexylthiophene (P3HT):fullerene derivative PCBM:Zinc oxide nanoparticles (ZnO-NP) by measuring its optical absorption, crystal structure and film surface morphology. Zinc oxide nanoparticle was prepared by sol-gel method. It has optical absorption below 370 nm and average particle size 40 nm as shown by TEM picture. Ternary thin blend films of P3HT:PCBM:ZnO-NP were prepared by use of spin-coating method. The UV-Vis spectrum of thin film contains absorption peaks originated from contribution of P3HT at wavelengths 520 nm, 550 nm and 600 nm, from contribution of PCBM at 260 nm and 330 nm and from ZnO-NP at wavelengths below 370 nm which confirms that these three materials were well mixed in the films. Its XRD pattern also contains the peaks from each of these three-materials. In this report, we compare surface morphology of thin films of pure P3HT, pure ZnO-NP, blend of P3HT:PCBM, blend of P3HT:ZnO-NP and ternary blend of P3HT:PCBM:ZnO-NP.

Performance of supercapacitor device model based on double layer reduced graphene oxides films as electrodes in KCl electrolyte

We report the performance of supercapacitor device model based on double layer reduced graphene oxide (rGO) films as electrode in 1 M KCl. Graphene oxide (GO) films were deposited on ITO-glass use an electrochemical deposition method using 1 mg/ml GO dispersed in water. The films thicknesses were controlled by number deposition cycles. rGO films were obtained by thermally reduced the GO films at 200°C for 1 hour under argon flowing. A pair of 1 cm2 rGO/ITO electrodes was employed as double layer electrodes of supercapacitor device model using a filter paper which was soaked in 1 M KCl as a separator. Performance of the supercapacitor model was investigated using cyclic voltammetry (CV) in a voltage range of 0.0 volts to +0.9 volts with varied scan rate range of 25mV/s to 125mV/s. The highest specific capacitance of 20 F/kg and specific power of 0.825 W/kg was obtained using device with rGO films that deposited for three voltage cycles.

Influences of Al dopant atoms to the structure and morphology of Al doped ZnO nanorod thin film

We report our work about dependency of Al dopant atoms to the growth process of Al doped ZnO (AZO) nanorod structure. ZnO is one of type metal oxide, which is classified as semiconducting material with direct wide band gap (~ 3.4 eV). This metal oxide is widely used in optoelectronic devices, such as solar cell, gas sensing, and photocatalyst. To produce effective photoelectrode in solar cell devices and high sensitive sensor in gas sensing application, many researchers have been modifying the nanostructure, such as inserting dopant ions, variation in deposition technique and surface modifications. By inserting some dopant ions/atoms, the structure and morphology of ZnO nanorod can be controlled. Nucleation process of nanorod structure which is growth by chemical solution method, are depend on seed layer morphology. We have prepared ZnO nanorod thin film (growth by self-assembly method) with inserting aluminum as dopant atom both in seed layer and nanorod growth solution. The morphology of ZnO nanostructured significantly changes as the existence of aluminum atoms. Based on X-ray diffraction pattern, the wurtzite structures of AZO nanorod still possessed and only affect to the small shift of lattice crystal. A high surface roughness of seed layer can produce wide radius of nanorod, since the nucleation process initiated by seed layer particle size as a template of nanorod arrangement.

Structural Properties of Perovskite Films on Zinc Oxide Nanoparticles-Reduced Graphene Oxide (ZnO-NPs/rGO) Prepared by Electrophoretic Deposition Technique

Perovskite solar cells highly believed as next generation solar cells to replace currently available inorganic silicon solar cells due to their high power conversion efficiency and easy processing to thin films using solution processing techniques. Performance and stability, however still need to be improved for mass production and widely used for public electricity generation. Perovskite solar cells are commonly deposited on Titanium Dioxide (TiO2) film as an effective electron transport layer (ETL). We used Zinc Oxide nanoparticles (ZnO-NPs) as ETL in perovskite solar cells due to the low temperature required for crystallization and can be formed into different shapes of nanostructures. However, perovskite film can easily degrade into insulating lead iodide due to deprotonation of the methylammoniumcation at the surface of ZnO-NPs, in particular when it stored in ambient air with high relative humidity. The degradation of perovskite layer is therefore needed to be overcome. Here, we capped ZnO-NPs with reduced graphene oxide (rGO) to overcome the degradation of perovskite film where ZnO-NPs is synthesized by sol-gel method. The average nanoparticle size of ZnO is 15 nm. ZnO-NPs and ZnO-NPs-rGO films are prepared using electrophoretic deposition technique, which can produce large area with good homogeneity and high reproducibility. The stability of perovskite layer can significantly be improved by capping ZnO with rGO, which is indicated by absence of color change of perovskite after storage for 5 (five) days in ambient air with relative humidity above 95%. Moreover, the X-Ray Diffaction peaks of perovskite film are more preserved when deposited on ZnO/rGO film than using only ZnO film. We strongly believe, by capping ZnO film with rGO, both the performance and stability of perovskite solar cells can be improved significantly.Perovskite solar cells highly believed as next generation solar cells to replace currently available inorganic silicon solar cells due to their high power conversion efficiency and easy processing to thin films using solution processing techniques. Performance and stability, however still need to be improved for mass production and widely used for public electricity generation. Perovskite solar cells are commonly deposited on Titanium Dioxide (TiO2) film as an effective electron transport layer (ETL). We used Zinc Oxide nanoparticles (ZnO-NPs) as ETL in perovskite solar cells due to the low temperature required for crystallization and can be formed into different shapes of nanostructures. However, perovskite film can easily degrade into insulating lead iodide due to deprotonation of the methylammoniumcation at the surface of ZnO-NPs, in particular when it stored in ambient air with high relative humidity. The degradation of perovskite layer is therefore needed to be overcome. Here, we capped ZnO-NPs with ...

Self-Assembly of ZnO-Nanorods and Its Performance in Quasi Solid Dye Sensitized Solar Cells

Zinc oxide (ZnO) nanorods (NRs) were successfully prepared by self-assembly methods using zinc nitrate hexahydrate and hexamethylenetetramine as raw materials. ZnO-NRs were grown on FTO/ZnO seed layer and to enhance dye adsorption it was continued by deposition of titania (TiO2) paste by screen printing method. Deposition time of ZnO-NRs were varied, for 120, 150 and 180 minutes and subsequently stacked with one layer of TiO2 mesoporous. The resulting heterojunction layers of FTO/ZnO-Nrs/TiO2 was then applied as a photoanode in quasi-solid dye sensitized solar cell (QS- DSSC) with polymer gel electrolyte (PGE) as a hole conductor. UV-Vis spectrometer was used to investigate the changes of dye adsorption in photoanode with/without inserting titania mesoporous. Characterizations of scanning electron microscopy (SEM) and X-ray diffraction was carried out and the results shows that increasing the deposition time produces a smaller average grain size, diameter and denser layer of ZnO-nanorods. From current-voltage measurement, higher efficiency (η = 2.53%) was obtained for 120 min ZnO nanorods with short circuit current density (Jsc ) of 2.84 mA/cm2 and open circuit voltage (Voc) of 0.7 V. The combination of TiO2 and ZnO-NRs shows a better performance in solar cells characteristics due to increases of dye adsorption on photoanode and high photogenerated electron transport rate. This work emphasizes an optimum condition of ZnO-NRs in combination with TiO2 mesoporous as an alternative photoanode in QS-DSSC.