organic solar cell

Organic solar cells are mostly flexible and lightweight—a good solution to low cost energy production, which can have a manufacturing advantages over inorganic solar cell materials. An organic solar cell uses organic electronics, which deals with conducting polymers or small organic molecules. In 1959, Kallamann and Pope reported a photovoltaic effect in a single crystal of anthracene which was sandwiched between two similar electrodes and illuminated from one side. But they could not explain the phenomenon completely

Among the different type of solar cells, organic solar cells based on a bulk heterojunction (BHJ) composites of conjugate polymers P3HT (poly 3-hexylthiophene) and PCBM (phynyl-C70 butyric acid methylester) that allow the maximum absorption of light and have been reported among the highest performing material for researchers investigation and studies [4-9] for improving their power conversion efficiencies. In organic solar cell, bulk heterojunction (BHJ) formed by an interpenetrating of a conjugate polymer and electron accepting molecules constitute a very promising route towards cheap and flexible solar cells [10-11] as recently exhibited in progress of automated roll-to-roll processing and solar cell stability [12-13].

The detail microscopic working mechanism in inverted organic solar cell can be explain from energy level diagram of figure 1.4. After absorption of incidents photons, excitons (pair of electron-hole) are produce in active layer (P3HT:PCBM). Separation of the pairs and collections of electrons and holes at electrodes are then required to ensure the conductivity of electricity in the cells. Electrons from donor material (P3HT) will travel from its LUMO band to ITO cathode through LUMO of PCBM and holes was collected at metal anode, Au from HOMO band of acceptor material (PCBM) through HOMO band of P3HT. However ITO is not suitable for electron collective electrode due to the large gap of electron volts (eV) between ITO and LUMO level of PCBM.

stead of the difference in (HOMO) level of the donor (PCBM) and the lowest unoccupied molecular orbital (LUMO) level of the acceptor (P3HT) for ohmic contact [13]. The stability of the organic solar cell is also a big concern as the cathode-material ion diffuses through the active layer which can react with the polymer and alter its semi-conducting properties [14]. Another degradation phenomenon is the formation of insulating metal-oxide layer at the cathode interface [15]. Therefore, stability can be improved by using efficient diffusion barrier ma- terial having less air sensitivity. Improvement of V OC and charge extraction has been done by modifying elec-

Here, we present a transparent planar heterojunction organic solar cell containing molecular organic donor and acceptor materials, which have peak-absorption in the ultraviolet (UV) and near- infrared (NIR) A trilayered ZnO/Ag/ZnO (ZAZ) transparent electrode is presented as the bottom electrode for this transparent organic solar cell. The optical and electrical properties of the electrode itself, and the electrode with the whole solar cell, is investigated by experiment and simulation. A second transparent electrode comprised of blended Ca and Ag is used as the top contact of the organic solar cell. This solar cell reached similar device performance with both top and bottom illumination, a feat that is uncharacteristic of most organic solar cells, which are constructed on transparent substrates with one opaque contact and can only function under bottom illumination [20]. This unique feature will allow this device to be easily incorporated into large solar arrays that are similar in design and layout to existing solar panels, thus providing a simple and effective strategy to create OPV arrays using existing manufacturing methods. In order to further improve the current density of the solar cell, an optimized distributed Bragg reflector (DBR) is used as a transparent NIR mirror with an average transmittance >95%. The transparent solar cell and the DBR deposited on PET substrate have similar device performance as the glass-based solar cells with top illumination, which makes it is possible to deposit arrays of this device on flexible substrates.

the advancement of new technology and development of organic solar cell, the price of photovoltaic is going down and encouraging large implementation of photovoltaic system. Due to the implementation of solar panels in locations that are often remote, it is very difficult to monitor physically. The traditional method of monitoring solar panels using PLC or SCADA systems is not cost effective. Therefore, with the development of advanced technology, we developed a data acquisition system using Internet of Things (IoT) technology. It is a new cost effective technology used to monitor organic solar cell using open source tools such as Integrated development environment and Thinkspeak. Thinkspeak is an IoT platform incorporated in Matlab that provides an environment to monitor solar panels parameters. This paper proposes a system for real-time data acquisition and remote monitoring of organic solar cells (OSC) incorporated in buildings facades for stability analysis. The system consists of embedded systems and sensors to monitor organic solar cells parameters such as current and voltage and weather conditions such as humidity, temperature and irradiation. The result of the proposed system has shown an efficient method for monitoring solar panels with an ability to display and store data in cloud. Also, during four months of observation the result has shown some preliminary delamination in the organic solar cell with a decrease in output power.

This paper describes the electrical conductivity, Hall Effect study, and efficiency in bulk hetero-junction organic solar cell (OSCs) by using natural pigments Allamanda Cathartica Linn (yellow bell flower) and Ixora coccinea L (Ixora flower). In this work, Indium Tin oxide (ITO) glass as substrate was heated at 50ÚC to 200ÚC. The polymer used was Poly (3- Dodecylthiophene) (P3DT) thin film. These OSCs are fabricated accordingly bulk of ITO/ P3DT+Allamanda Cathartica Linn via electrochemistry method at room temperature. The electrical conductivity of sample was explored by four point probes (FPP) under dark and under light radiation (range of 10 Wm -2 to 200Wm -2 ). FPP data revealed that electrical

The organic solar cell structure if seen from the side view is designed as Figure 1. First, the ITO substrate was cleaned using ultrasonic cleaning bath in the acetone isoprophyl alcohol, and then dried using dry nitrogen. A conductive layer of banana flower extract anthocyanin with thickness of 40 mm was coated on the substrate using spincoater. At this step, some parameters were controlled to optimize the conductive layer thickness. The thickness, optical property and microstructure were also optimized. The aluminium electrode in thickness of 120 nm was formed through thermal evaporation at vacuum condition 1,33 x 10 -4 Pa.

In the recent years, significant attention has been paid to the organic solar cells (OSCs) based on bulk-heterojunction (BHJ) materials, due to their low manufacturing cost and potential applications in the field of flexible and large-area solar cells [1]. It could be said that poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl-C61 butyric acid methyl ester (PCBM) are considered as the most investigated materials for OSCs [2]. The inverted organic solar cells (IOSCs) exhibit competitive performance and offer better stability compared with the traditional OSCs [3]. The nature of the contacts on both sides of the active layer is considered as an essential feature to determine the OSCs parameters, hence the final power conversion efficiency (PCE) [4]. Titanium dioxide (TiO 2 ) films are used in

UV range of 300 to 400 nm and acts as an electron ac- ceptor to transport such electrons to the electrode [9,13]. The fabrication process and experimental proce- dures are described in Figure 1 and the ‘Methods’ sec- tion. This strategy has the following merits: Firstly, the pillar size can be well controlled as regards diameter, interval, and height, making it close to the exciton dif- fusion length. Secondly, a carrier pathway can be formed, which is directly connected to the electrodes. Finally, self-standing pillars can be fabricated uniformly over a large area. Besides, with this technology, costly imprinting equipment and cumbersome processes like dry etching [14,15] are avoidable. By employing these advantages, we demonstrate the fine-tuning of nanos- tructures for organic solar cells and report preliminary device properties.

18. T. Kuwabara, C. Iwata, T. Yamaguchi, K. Takahashi. Mechanistic Insights into UV-Induced Electron Transfer from PCBM to Titanium Oxide in Inverted- Type Organic Thin Film Solar Cells Using AC Impedance Spectroscopy. ACS Applied Materials & Interfaces. Vol 2, 2010, pp. 2254-2260.

Jo J., J. Pouliot, D. Wynands, S. Collins, J. Kim, T. Nguyen, H. Woo, Y. Sun, M. Leclerc, A.J. Heeger, 2013. Enhanced efficiency of single and tandem organic solar cells incorporating a diketopyrrolopyrrole-basedlow-bandgap polymer by utilizing combined ZnO/polyelectrolyte electron-transport layers, Adv. Mater. 25;4783–4788. Kim K., Y. Kim, W. Kang, B. Kang, S. Yeom, D. Kim, J.

during the last few years and are becoming established as one of the future photovoltaic technologies for low-cost power production. During last 10 years lot of work has been done on this technology. Some of them are polymer fullerene solar cells, small molecule and hybrid solar cells. The most successful of them are the polymer–fullerene solar cells that comprise a mixture of the polymer, which is the donor material and a fullerene material as the acceptor material. While research on organic solar cells date back to the 1980s the first example of a polymer solar cell was the bi-layer hetero junction between the soluble polymer and the Buckminsterfullerene C60 where a power conversion efficiency of 0.04% was obtained using monochromatic light. The next convincing step was the application of a dispersed bulk hetero-junction of MEHPPV and C60 and later soluble derivatives of C60 which increased the power conversion efficiency to 2.5%. The third step is The most important physical means for improving performance are the use of a thin layer of an insulator between the active layer and the low work function metal electrode and more recently also in inverted devices, the use of optical spacers, the understanding of how the open circuit voltage is obtained and by these means deriving an efficient method for predicting performance of materials combinations based on measurable materials properties .

The photovoltaic definition of OSC can be described as a process of converting solar light (photon) to electricity (voltage). In OSC cells, the structure of the cell can be categorized into two: (i) the conjugated polymers and (ii) the small organic molecules. The conjugated polymers also are known as bulk-heterojunction solar cells, where the mechanism of the electricity generation is dependent on the electron donor and acceptor inside the polymers. OSC cells are distinguished from the inorganic photovoltaic cells such as silicon-based by its major materials and electrical operation. The efficiency of inorganic solar cells can reach 20% while the best OSC based on bulk-heterojunction structure operate at 3-5% efficiency.

photovoltaic power production units integrated into our daily lives. That being said, their efficiency levels are still below that of standard solar cells and scientists are working to improve this crucial aspect in order to commercialize this new technology. The organic solar cells have a similar function but their architecture is 2000 times thinner (about 100 nm), blending different layers of organic materials and semiconductors. The notable advantage in these organic solar cells is that they are much cheaper to produce than conventional solar cells, a huge advantage for its possible commercialization. However, the high manufacturing cost and the rate of converting sunlight into electricity (known as the electrical energy conversion efficiency rate) are drawbacks that have impeded the widespread use of solar energy technology. Other factors exist as well, such as the time constraint associated with sunlight and the availability of the raw materials, but these are either impossible to change (number of hours of available sunlight) or tied into the main drawbacks of cost and efficiency (raw material availability). Improvements, therefore, are both warranted and necessary [12].Thankfully, improvements have been made in order to reduce the manufacturing costs and improve the efficiency rate. From first generation silicon solar cells, which can be considered the technological backbone of the solar energy industry, second and third generations have been developed and deployed. One particular third-generation solar cell, the organic solar cell, is slated to offer a reduction in the cost of manufacture.

In summary, this paper presents the deposition of highly reflecting and conducting metallization thin films to be used as a cathode electrode of an organic solar cell. A metal thin film with low resistivity (ca. 4.2 × 10 − 4 Ω.cm) and high visible-light-reflectance (ca. 90%; bandgap, 3.71 eV) can be achieved on films using a conventional evaporation process, those characteristics are comparable to those of metal films deposited on a glass substrate. The metal films obtained here are applicable to various optoelectronic devices such as solar cells and even organic light emitting diodes.

diketopyrrolopyrrole (DPP) units within the conjugated backbone and reported its performance in OFETs under ambient conditions. Optical, thermal, and electrochemical properties as well as the nanomorphology of this polymer indicated that it is a promising material for OFET and OPV applications. 11 Here, we report a more in-depth study of the material’s performance in solar cells and its optical character- istics. In particular, we have found a remarkable power conversion e ffi ciency for the single material organic solar cell (SMOC) with p(DPP-TTF) as the sole semiconductor material. These values are comparable to those fabricated from donor/acceptor SMOCs. 19 Recently, a SMOC fabricated from a copolymer consisting of P3HT and C 60 repeat units gave

Charge carrier thermalisation, in the form of a time-dependent mobility, was studied in three different polymer:fullerene blends using two different experimental techniques. The photo-CELIV technique was applied to poly[3,6-dithiophene-2-yl- 2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-naphthalene] (PDPP-TNT) : [6,6] phenyl-C71-butyric-acid-methyl-ester (PC70BM) [220] solar cells. A shift in the current maximum with increasing delay time was observed, as has previously been reported in other organic solar cell systems [137, 138]. However, numeric simulation with a drift-diffusion model demonstrated that this shift is induced by the measure- ment technique and does not necessarily indicate a genuine time-dependence in the mobility. Quantitative analysis of the observed data revealed that carrier mobility is not time-dependent in this system. This highlights a weakness of the photo-CELIV technique: variations in the experimental conditions might induce artificial trends into the apparent mobility. We also examined the impact of dispersion on photo-CELIV transients, and found that a systematic change in the apparent mobility occurs when the amount of dispersion is varied, even if the true mobility is held constant. This would be complicate temperature-dependent studies, since the amount of dispersion is often dependent upon temperature. It was concluded that care must be taken when examining trends in mobility obtained via photo-CELIV.

The main difference between the conventional and inverted organic solar cells is there device structure. The both exhibits same type of electrical characteristics. And both the D/A and E/P interface have critical effect on their efficiency. Based on our experimental results we used the above model to explain the electrical characteris- tic of the inverted organic solar cell. The I-V characteristics curve from simulation and experimental data is shown in Figure 7. In Figure 8, the I-V characteristics curve for 1.0% at. Y-doped ZnO is shown along with the proposed model and other previously discussed models. Figure 8 shows that proper correlation is achieved be- tween the experimental and simulated I-V plots. And it is clear from Figure 8 that our previous proposed model can successfully describe the electrical characteristics of Y-doped ZnO inverted solar cells. Table 2 shows the data for inverted organic solar cells fabricated at different concentration of yttrium, using solution

In conclusion, the organic solar cells based on nanohole- type and nanopillar-type patterned metallic electrodes have been investigated systematically by comparing their similar- ities and differences. It has been demonstrated that both of the patterned metallic electrode-based organic solar cells can outperform the planar control with an enhanced light trapping effect in the active layer if optimal designs are uti- lized. The integrated absorption efficiencies over the inves- tigated wavelength range for the two optimal patterned metallic electrode-based organic solar cells are approxi- mately the same (82.4%), leading to a 9.9% enhancement factor compared to that of the control. Given that the thick- ness of the active layer in the organic solar cell with either type of patterned metallic electrode is the same as that of the control (which produces the first absorption peak due to cavity resonance), the organic solar cells with patterned metallic electrodes can maintain the carrier transport prop- erties of the planar control device but with enhanced ab- sorption and less active materials. The improved light trapping effects for the two different organic solar cells have also been clarified by analyzing the field distributions at the enhancement peaks. The nanohole-type patterned metallic electrode can excite the dipole-like localized plasmon reso- nances and propagating surface plasmon polaritons which are localized at the top of metallic ridges. The nanopillar- type patterned metallic electrode can also excite the dipole- like localized plasmon resonances and propagating surface plasmon polaritons which are localized at the top of metal- lic nanopillars. In addition, grating-coupled surface plas- mon polariton modes at the bottom of patterned metallic electrodes are also excited, yielding multiple peaks superim- posed over the broad enhancement bump at the wave- length range shorter than 600 nm. The integrated absorption efficiency is optimized with the periodicity of 350 nm when the localized resonant modes are hybridized with the bent surface modes only over the short wavelength range. In a comprehensive view, the nanopillar-type pat- terned metallic electrode is suggested to be applied in the present organic solar cell system, since its optimal design has a moderate filling ratio, which is much easier to process than its counterpart. The proposed study is expected to contribute to the development of high-efficiency organic solar cells.