Materials Data-science Approach for Comprehensive Understanding of Organic Thin Film Solar Cells

As organic solar thin films fabricated by an active layer of organic materials are economical, lightweight, and flexible, as well as facilitating processing, organic solar cells have attracted considerable attention within the past few decades as a clean energy source. With this in mind, there have been global investigations and studies of the power conversion efficiency (PCE) within organic solar cells. In organic thin-film solar cells, the effect of the performance is not only dependent on an adopted active material but also the molecular orientation on the electrode. Using the mixed solution of Poly (3-hexylthiophene) and PCBM, both dissolved by solvent, an organic thin film is fabricated using the paint method (The conceptual diagram of the paint method is shown in Fig. 1) The form of the thin film was evaluated, an organic thin-film solar cell using the paint method for the active layer was made, and its performance was evaluated and examined. Using the mixed solution of Poly(3-hexylthiophene) and PCBM, both dissolved by solvent, an organic thin film is fabricated using the paint method (The conceptual diagram of the paint method is shown in Fig. 1) The morphology of the thin film was evaluated using an AFM image, UV/vis spectra, and so forth. Based on these data, an organic thin-film solar cell that used the paint method for the active layer was fabricated, and the performance was evaluated and examined. For the organic thin film solar cell fabricated using the brush painting method, the open-circuit voltage (Voc) is 0.41 V, the short circuit current density (Jsc) is 2.07 mA/cm2, and the fill factor is 0.34. The efficiency η of PCE becomes 0.29%.

As organic thin film solar cells fabricated by the active layer of organic materials are economical, lightweight, and flexible, as well as generating no CO 2 and being easy to fabricate, they have attracted significant attention as green energy sources from a past decade to date. Therefore, their power conversion efficiency (PCE) has been investigated and studied worldwide. In organic thin-film solar cells, the effect of the performance depends not only on the adopted active material but also relates to the molecular orientation on the electrode. Using a mixed solution of Poly(3-hexylthiophene) and PCBM, both of which were dissolved in a solvent, the organic thin films were fabricated using the paint and spray methods, while the morphology of the thin film was evaluated by an AFM image, UV/vis spectra, and so forth. Based on these data, an organic thin-film solar cell using both solution methods for the active layer was fabricated, and the performance evaluated and examined. For organic thin film solar cells fabricated using a spin-coating method, the open-circuit voltage (Voc) is 0.41V, the short circuit current density (Jsc) is 2.07mA/cm 2 , and the fill factor is 0.34, while the efficiency η of PCE become 0.29%. In the spray method, the short circuit current (Isc) is 2.5 mA/cm 2 , the open circuit voltage (Voc) is 0.45 V, the fill factor (FF) is 0.28, and the power conversion factor (PCE) 0.35%. The area of organic solar cells fabricated by spin coating and spray methods is 1 cm 2 respectively. The organic solar cells are not thermally treated, and hence have high respective power conversion efficiencies.

We demonstrate theoretically that by embedding plasmonic honeycomb nanoantenna arrays into the active layers of inorganic (c-Si) and organic (P3HT:PCBM/PEDOT:PSS) thin film solar cells, absorption efficiency can be improved. To obtain the solar cell absorption spectrum that conforms to the solar radiation, spectral broadening is achieved by breaking the symmetry within the Wigner-Seitz unit cell on a uniform hexagonal grid. For optimized honeycomb designs, absorption efficiency enhancements of 106.2% and 20.8% are achieved for c-Si and P3HT:PCBM/PEDOT:PSS thin film solar cells, respectively. We have demonstrated that the transverse modes are responsible for the enhancement in c-Si solar cells, whereas both the longitudinal and transverse modes, albeit weaker, are the main enhancement mechanisms for P3HT:PCBM/PEDOT:PSS solar cells. For both inorganic and organic solar cells, the absorption enhancement is independent of polarization.

An analysis was conducted herein on the research status of several popular solar cells at the present stage, including silicon solar cell, thin film photovoltaic cell, and dye-sensitized solar cell (DSSC). In doing so, we concluded that the current situations provide a favorable objective environment for the popularization of organic thin film solar cells. Finally, we reviewed the merits and demerits of the organic thin film solar cell together with the major research focus on and progress of it, and summarized obstacles to and development trails of the popularization of organic thin film solar cells.

In this paper, we study experimentally the enhancement of parameters of a typical organic thin film solar cell (OSC) achieved by an originally proposed light trapping structure (LTS). Our LTS is an array of silver nanoantennas supporting collective modes, what provide subwavelength light enhancement in the substrate. Low losses in the metal result from the advantageous optical field distribution that is achieved in the broad range of wavelengths. We study the enhancement of all the main photovoltaic (PV) parameters observed in OSC with our LTS, such as power conversion efficiency (PCE), which is effectively increased by 18%, fill factor (FF), that can also be effected positively and short-circuit current Isc improvement. Although the Ag nanoantenna occupies up to 40% of the photoactive OSC area, it provides the nearly twice enhanced optical absorption, resulting in overall higher Isc and FF. Improvements of the optical and electrical design of OSC architectures are discussed for further enhancement of per...

This thesis discusses the results of the investigations on the use of plasmon metal nanoparticles (NPs) to enhance the performance of polymer solar cells, which are promising alternative solar energy converters to silicon-based solar cells. Polymer solar cells offer a cost-effective, flexible solar panel using a solution processing method for the generation of power from solar sources. Several key factors are considered to achieve this goal, including optical absorption, nano-morphology, and charge carrier mobility. The thesis focuses on investigating the potential of various dopants, such as solvent additives, thermal annealing, and metal nanoparticles (NPs), to improve the performance of thin-film organic solar cells (TFOSCs) by enhancing the charge transport processes. This research employed conventional device architectures to study the effectiveness of the active and buffer layers on charge transport and stability. The results have already been published in several internationally referred journals. In this thesis, the synthesized metal NPs were employed as mechanisms to improve the performance of TFOSC incorporated with poly-3-hexylthiophene (P3HT) as the donor material and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as the acceptor material. The popular metal NPs such as nickel, (Ni), zinc (Zn), silver (Ag), calcium (Ca), sulfur (S), and cobalt (Co) were used to synthesize various bimetallic composites. Bimetallic nanoparticles such as nickel-doped with zinc bimetallic (Ni/Zn), silver-doped with calcium (Ag/Ca), silver-doped with cobalt (Ag/Co), and silver-doped zinc sulfide (ZnS/Ag) were employed at different functional layers of solar cell structure. Hence, the study employed various spectrometers such as high-resolution transmission and scanning electron microscopy (HRTEM and HRSEM), X-ray diffraction, Ultraviolet-Visible (UV-Vis) spectroscopy to investigate the size, morphology, elemental mapping, and optical properties of synthesized metal NPs. HRTEM is indeed a powerful technique for characterizing nanoscale materials, and it can provide valuable insights for confirming the presence of core-shell structures in NPs. Compared to the pristine reference, the blend of metal NPs with active and buffer layers at different concentrations plays a crucial role in augmenting the optical and electrical properties in TFOSC devices. Such increment of optical and electrical properties in this thesis is due to improved short-circuit current (Jsc), fill factors (FFs), and charge carrier mobility, which are significant to enhance the power conversion efficiency (PCE) values in the polymer solar cells. These prominent improvements are due to the presence of localized surface plasmonic resonance (LSPR) effect of TFOSCs. Finally, this thesis provides a series of experimental works fabricated with several metal NPs in TFOSCs at different concentrations. Iqoqa. Lo mbhalo weziqu zobudokotela uxoxa ngemiphumela yophenyo ngokusetshenziswa kwe-plasmon metal nanoparticles (NPs) ukuthuthukisa ukusebenza kwamaseli elanga e-polymer, athembisa ezinye iziguquli zamandla elanga kumaseli elanga asekelwe ku-silicon. Amaseli elanga e-polymer anikeza iphaneli yelanga engabizi kakhulu, eguquguqukayo esebenzisa indlela yokucubungula isisombululo sokukhiqiza amandla avela emithonjeni yelanga. Kucatshangelwa izici ezimbalwa ezibalulekile ukufeza lo mgomo, okuhlanganisa ukumuncwa kwe-optical, i-nano-morphology, kanye nokuhamba kwenkampani yenethiwekhi. Lo mbhalo weziqu zobudokotela ugxile ekuphenyeni amandla ama-dopant ahlukahlukene, njengezithasiselo ezincibilikayo, i-thermal annealing, nama-NPs ensimbi, ukuze kuthuthukiswe ukusebenza kwamaseli elanga aphilayo (TFOSCs) amafilimu amancane ngokuthuthukisa izinqubo zokuthutha zokushaja. Lolu cwaningo lusebenzise izakhiwo ezijwayelekile zedivayisi ukuze kufundwe ukusebenza kahle kwezingqimba ezisebenzayo kanye nebhafa ekuthuthweni kokushaja nokuzinza. Imiphumela isivele ishicilelwe kumajenali amaningana okukhulunywa ngawo emhlabeni jikelele. Lo mbhalo weziqu zobudokotela, ama-NP ensimbi ahlanganisiwe aqashwe njengezindlela zokuthuthukisa ukusebenza kwe-TFOSC ehlanganiswe ne-poly-3-hexylthiophene (P3HT) njengento yokunikela kanye ne-[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) njengento eyamukelayo. Ama-NP ensimbi adumile afana ne-nickel, (Ni), i-zinc (Zn), isiliva (Ag), i-calcium (Ca), isulfure (S), ne-cobalt (Co) asetshenziselwa ukuhlanganisa izinhlanganisela ezihlukahlukene ze-bimetallic. Ama-nanoparticles e-Bimetallic afana ne-nickel-doped ne-zinc bimetallic (Ni/Zn), i-silver-doped ene-calcium (Ag/Ca), i-silver-doped ne-cobalt (Ag/Co), kanye ne-silver-doped zinc sulfide (ZnS/Ag) asetshenziswa izendlalelo ezahlukene zokusebenza zesakhiwo samaseli elanga. Ngakho-ke, ucwaningo lusebenzise ama-spectrometer ahlukahlukene afana ne-high-resolution transmission kanye ne-scanning electron microscopy (HRTEM kanye ne-HRSEM), i-X-ray diffraction, i-Ultraviolet-Visible (UV-Vis) spectroscopy ukuze kuphenywe usayizi, i-morphology, i-elemental mapping, kanye nezakhiwo zamehlo. yama-NP ensimbi ahlanganisiwe. I-HRTEM iyindlela enamandla ngempela yokuhlukanisa izinto ze-nanoscale, futhi inganikeza imininingwane ebalulekile yokuqinisekisa ubukhona bezakhiwo zamagobolondo ayinhloko kuma-NP. Uma kuqhathaniswa nereferensi emsulwa, inhlanganisela yama-NPs ensimbi anezendlalelo ezisebenzayo kanye nebhafa ezindaweni ezigxilile idlala indima ebalulekile ekwandiseni izici zokubona nezikagesi kumadivayisi e-TFOSC. Lokhu kuthuthukiswa okuvelele kungenxa yobukhona bomphumela wendawo we-plasmonic resonance (LSPR) wama-TFOSC.

Many R&D activities currently concentrate on low-cost production concepts for photovoltaics. Because of their low material price organic thin film cells possess the potential to provide module market prices below $1/Wp. In this publication we report on the development of a roll-to-roll production technology for the monolithic series connection of organic thin film solar cells based on laser structuring. Due to the different material properties of the layers, structuring experiments are performed with a broad range of laser sources. Various parameters like wavelength (e.g. 355 nm, 532 nm, and 1064 nm), pulse durations, pulse energy and spot-to-spot overlap are studied to obtain a profound understanding of the laser-material interaction mechanisms. The focus of the experiments is to obtain an optimal edge quality without damaging the layer structure. Results are presented, obtained with optimized parameters for the laser structuring of the several layers used in organic thin film modules. Good results are obtained with lasers with nanosecond pulse durations and wavelengths of 1064 nm and 532 nm, depending on the processed layer. Processing speeds>1 m/s are realized, as required in industry. Optical and scanning electron microscope images are used to analyze the quality of the structuring. Furthermore, the electrical performance of the modules is analyzed to show the applicability of the technology for future mass production of organic solar modules.

Macromolecules Containing Metal and Metal‐Like Elements

Photovoltaic technology has a range of applications nowadays. Organic solar cell research has developed in recent years. Common materials for organic solar cells are phthalocyanines. In this paper it is presented a discussion of the fundamentals of photovoltaic technology, photovoltaic effect, organic solar cells, phthalocyanines and Gallium Arsenide reconstructed surfaces. Also it is studied the behavior of lead pthalocyanine (PbPc) in substrates of Gallium Arsenide-GaAs (001) with reconstruction surface Arsenide (As) stoichiometric β2(2x4). It is an analysis and study of innovative organic solar cells. The reason for this study is that PbPc is an organic molecule with very good optoelectronic properties, promising to be used in organic thin film solar cells or combination of organic and inorganic layers solar cells. In research is the behavior of phthalocyanines according to the surfaces of the substrates. The experimental photovoltaic characterization of a solar cell from lead phthalocyanine is presented. The efficiency of potential solar cells is estimated by measuring the photocurrent spectra. The understanding of the material and the samples combinations is important for potential applications and improvements for the use of solar cells.

Nanocrystal N-Zn-Ag/TiO2 powders were prepared with N-Zn/TiO2 by photo deposition method. A series of pure polymers P3HT[poly(3-hexylthiophene)], P3OT[poly(3-octylthiophene)], P3DT[poly(3-decylthiophene)] and P3DDT[poly(3-dodecylthiophene)], was synthesized, which were used to synthesize p-n type semiconductor materials P3HT/N-Zn-Ag-TiO2, P3OT/N-Zn-Ag-TiO2, P3DT/N-Zn-Ag-TiO2 and P3DDT/N-Zn-Ag-TiO2 by in situ chemical method. X-Ray diffraction(XRD) and infrared(IR) spectroscopy showed the structure of the polymers and complexes. Ultraviolet-visible(UV-Vis) spectra and cyclic voltammograms(CV) showed the optical and electronic performance of the polymers and complexes. Two new single and double organic thin film heterojunction solar cells were prepared with the above mentioned synthesized powders as raw materials. Current-voltage(I–V) measurements indicate that the conversion efficiency of the single organic thin film heterojunction solar cell is higher than that of the double organic thin film heterojunction solar cells. Single organic thin film heterojunction solar cells based on P3DT/N-Zn-Ag-TiO2 can get a photoelectric conversion efficiency of 0.0408%. The performance of electronic transform between electron donor and acceptor on organic thin film solar cells was researched.

Organic photovoltaic solar cells consist of organic semiconductors have attracted valuable importance in the areas of electronics and photonics during the last decade. Organic semiconductors are more flexible and less expensive substitute to inorganic semiconductors. By using simple and environmental friendly techniques, organic solar cells provide the possibility of fabricating large area, cost-effective, flexible, light-weight devices. An organic solar cell consists of an organic active layer which consider the basic steps in photovoltaic conversion such as light absorption, charge carrier generation, charge carrier transport and injection of charge carriers through the contact electrodes. Effect of Rs and Rsh in equivalent of circuit of photovoltaic diode discussed. P3HT:PCBM use as promising material for active layer. Stability and power conversion efficiency might be step-downs. By reducing these main challenges organic thin film solar cell can be part of solar cell market. Graphene sheet has great quality to replace indium tin oxide as cathode material. For simulation of bilayer organic solar cell determined that getting optimizing efficiency by maximizing values of exciton diffusion range, necessity of increase in electron hole mobility by applying horizontally external electric field, and lesser the donor accepter interface. Bulk heterojunction maximise the donor-acceptor contact area compare to bilayer heterojunction organic solar cell.

Dialkoxymethano[60]fullerenes as electron acceptors in thin-film organic solar cells

Organic thin film solar cells show generally lower power conversion efficiencies than those of the solar cells based on inorganic active materials. To solve the problem diverse research works have been tried: development of new organic semiconductors; modification of internal structure of active layers by means of organic solvent; design and fabrication of vertical device structure; introduction of buffer layer on the side of cathode electrode. Nevertheless, the buffer layer on the side of anode has not been fully optimized. This study is focused on the representative anode-side-buffer layer of Poly(3,4-ethylenedioxythiophene)(PEDOT): poly(styrenesulfonate) (PSS). PEDOT:PSS is an excellent conducting polymer material with favorably high optical transparency for almost entire range of visible wavelength, which is widely used for organic thin film solar cells as well as for other organic material based electronic devices such as organic light emitting diodes. Aiming for further performance enhancement of organic thin film solar cell device, an optimized condition was studied on the PEDOT:PSS by means of the thickness control and modification of the internal structure via addition of different organic solvents in mixture solution for thin film process.

Organic solar cells (OSCs) have attracted intense attention in recent years due to their advantages of low cost, easy fabrication, and high flexibility compared to its inorganic counterparts. However, due to the conflicts between the short diffusion length of excitons and long absorption length of incident photons, the thickness of OSCs is typically thin, and thus power conversion efficiency (PCE) is generally lower than traditional silicon solar cells. Therefore, an exquisite design of light trapping schemes is essential to the PCE improvement. Generally, physical guideline of light trapping involves two main approaches: geometric optics methods and wave optics methods. The former aims at elongating optical path inside the photoactive layer and thus enhancing photon absorption. For organic thin film solar cells with typical active layer thickness of 100 nm-200 nm, which is in subwavelength scale, we cannot investigate light harvesting mechanism simply by the geometric optics methods and instead wave optics properties should be considered. 
\nIn this thesis, two different light trapping enhancement designs are proposed. In order to simulate these structures, we built up programs for absorption power calculation based on scattering matrix method (SMM) by rigorously solving Maxwell’s equations. It is worth to point out that, different from the widely-used calculation method by Absorption = 1-Transmission-Reflection, our algorithm can extract the net optical absorption of the active layer rather than the whole OSCs. This improvement is very important because metal absorption, which does not contribute to exciton generation, can be excluded from the result. 
\nIn Chapter 3, design of organic solar cell incorporating periodically arranged gradient type active layer is presented. This design can enhance light harvesting with patterned organic materials themselves (i.e. self-enhanced active layer design) to avoid degrading electrical performance in contrast to introducing inorganic concentrators into the active layers such as silicon and metallic nanostructures. Our numerical results show that the OSC with a self-enhanced active layer, compared with the conventional planar active layer configuration, has broadband and wide-angle range absorption enhancement due to better geometric impedance matching and prolonged optical path. 
\nIn Chapter 4, OSC with interstitial lattice patterned metal nanoparticles (NPs) is proposed, which can improve the light blocking of traditional square lattice patterned NPs structure and achieve broadband absorption enhancement. Compared to square lattice design, the plasmonic mode couplings between individual NPs in the interstitial lattice are more versatile and much stronger. Moreover, plasmonic modes can couple to the guided modes, resulting in large enhancement factor at some wavelengths. These works provide a theoretical foundation and engineering reference for high performance OSC designs.

The fabrication method of plasmonic nanodots on ITO or nc-ZnO substrate has been developed to improve the efficiency of organic thin film solar cells. Nanoscale metallic nanodots arrays are fabricated by anodic aluminum oxide (AAO) template mask which can have different structural parameters by varying anodization conditions. In this paper, the structural parameters of metallic nanodots, which can be controlled by the diverse structures of AAO template mask, are investigated to enhance the optical properties of organic thin film solar cells. It is found that optical properties of the organic thin film solar cells are improved by finding optimization values of the structural parameters of the metallic nanodot array.