scholarly journals Effect of Flank Rotation on the Photovoltaic Properties of Dithieno[2,3-d:2′,3′-d′]benzo[1,2-b:4,5-b′]dithiophene-Based Narrow Band Gap Copolymers

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 239 ◽  
Author(s):  
Mingjing Zhang ◽  
Liangjian Zhu ◽  
Pengzhi Guo ◽  
Xunchang Wang ◽  
Junfeng Tong ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
Density Functional ◽  
Short Circuit ◽  
Energy Levels ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Photovoltaic Properties ◽  
Time Resolved ◽  
Dissociation Probability ◽  
Highest Occupied Molecular Orbital

Side chain engineering has been an effective approach to modulate the solution processability, optoelectronic properties and miscibility of conjugated polymers (CPs) for organic/polymeric photovoltaic cells (PVCs). As compared with the most commonly used method of introducing alkyl chains, the employment of alkyl-substituted aryl flanks would provide two-dimensional (2-D) CPs having solution processability alongside additional merits like deepened highest occupied molecular orbital (HOMO) energy levels, increased absorption coefficient and charger transporting, etc. In this paper, the triple C≡C bond was used as conjugated linker to decrease the steric hindrance between the flanks of 4,5-didecylthien-2-yl (T) and dithieno[2,3-d:2’,3’-d’]benzo[1,2-b:4,5-b’]dithiophene (DTBDT) core. In addition, an alternating CP derived from 4,5-didecylthien-2-yl-ethynyl (TE) flanked DTBDT, and 4,9-bis(4-octylthien-2-yl) naphtho[1,2-c:5,6-c’]bis[1,2,5]thiadiazole (DTNT), named as PDTBDT-TE-DTNT, was synthesized and characterized. As compared with the controlled PDTBDT-T-DTNT, which was derived from 4,5-didecylthien-2-yl flanked DTBDT and DTNT, the results for exciton dissociation probability, density functional theory (DFT), time-resolved photoluminescence (PL) measurements, etc., revealed that the lower steric hindrance between TE and DTBDT might lead to the easier rotation of the TE flanks, thus contributing to the decrease of the exciton lifetime and dissociation probability, finally suppressing the short-circuit current density (JSC), etc., of the photovoltaic devices from PDTBDT-TE-DTNT.

scholarly journals Ultrathin Cu(In,Ga)Se2 Solar Cells with Ag/AlOx Passivating Back Reflector

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4268
Author(s):  
Jessica de Wild ◽  
Gizem Birant ◽  
Guy Brammertz ◽  
Marc Meuris ◽  
Jef Poortmans ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Solar Cells ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Electron Microscopic ◽  
Current Increase ◽  
Time Resolved ◽  
Cigs Solar Cells

Ultrathin Cu(In,Ga)Se2 (CIGS) absorber layers of 550 nm were grown on Ag/AlOx stacks. The addition of the stack resulted in solar cells with improved fill factor, open circuit voltage and short circuit current density. The efficiency was increased from 7% to almost 12%. Photoluminescence (PL) and time resolved PL were improved, which was attributed to the passivating properties of AlOx. A current increase of almost 2 mA/cm2 was measured, due to increased light scattering and surface roughness. With time of flight—secondary ion mass spectroscopy, the elemental profiles were measured. It was found that the Ag is incorporated through the whole CIGS layer. Secondary electron microscopic images of the Mo back revealed residuals of the Ag/AlOx stack, which was confirmed by energy dispersive X-ray spectroscopy measurements. It is assumed to induce the increased surface roughness and scattering properties. At the front, large stains are visible for the cells with the Ag/AlOx back contact. An ammonia sulfide etching step was therefore applied on the bare absorber improving the efficiency further to 11.7%. It shows the potential of utilizing an Ag/AlOx stack at the back to improve both electrical and optical properties of ultrathin CIGS solar cells.

scholarly journals Photoactive Layer of DSSCS Based on Natural Dyes: A Study of Experiment and Theory

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Yuanzuo Li ◽  
Huixing Li ◽  
Peng Song ◽  
Chaofan Sun
Keyword(s):  
Density Functional ◽  
Short Circuit ◽  
Dye Sensitized Solar Cells ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Natural Dyes ◽  
Pheophytin A ◽  
Charge Difference Density ◽  
Forsythia Suspensa

Three natural dyes (Forsythia suspensa, Herba Violae, and Corn leaf) have been investigated as potential sensitizers for dye-sensitized solar cells. UV-vis absorption spectra reveal that three natural dyes mainly contain the compound of pheophytin a. Among three DSSCs, the highest photo electronic conversion efficiencyηis 0.96% with open circuit voltage (VOC) of 0.66 V, short circuit current density (ISC ) of 1.97 mA cm−2, and fill factor (ff) of 0.74. Theoretical time-dependent density functional theory and charge difference density are used to explore the nature of excited states. Results demonstrate that the first state is an intramolecular charge transfer (ICT) state, and electron injection could occur owing to the thermodynamically driving force.

scholarly journals Molecular-level architectural design using benzothiadiazole-based polymers for photovoltaic applications

2017 ◽  
Vol 13 ◽  
pp. 863-873 ◽  
Author(s):  
Vinila N Viswanathan ◽  
Arun D Rao ◽  
Upendra K Pandey ◽  
Arul Varman Kesavan ◽  
Praveen C Ramamurthy
Keyword(s):  
Molecular Orbital ◽  
Architectural Design ◽  
Density Functional ◽  
Short Circuit ◽  
Energy Levels ◽  
Photovoltaic Performance ◽  
Hole Mobility ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Lowest Unoccupied Molecular Orbital

A series of low band gap, planar conjugated polymers, P1 (PFDTBT), P2 (PFDTDFBT) and P3 (PFDTTBT), based on fluorene and benzothiadiazole, was synthesized. The effect of fluorine substitution and fused aromatic spacers on the optoelectronic and photovoltaic performance was studied. The polymer, derived from dithienylated benzothiodiazole and fluorene, P1, exhibited a highest occupied molecular orbital (HOMO) energy level at −5.48 eV. Density functional theory (DFT) studies as well as experimental measurements suggested that upon substitution of the acceptor with fluorine, both the HOMO and lowest unoccupied molecular orbital (LUMO) energy levels of the resulting polymer, P2, were lowered, leading to a higher open circuit voltage and short circuit current with an overall improvement of more than 110% for the photovoltaic devices. Moreover, a decrease in the torsion angle between the units was also observed for the fluorinated polymer P2 due to the enhanced electrostatic interaction between the fluorine substituents and sulfur atoms, leading to a high hole mobility. The use of a fused π-bridge in polymer P3 for the enhancement of the planarity as compared to the P1 backbone was also studied. This enhanced planarity led to the highest observed mobility among the reported three polymers as well as to an improvement in the device efficiency by more than 40% for P3.

Influence of Silicon Texturization on the Photovoltaic Properties of CuPc/n-Si Hybrid Solar Cells

2012 ◽  
Vol 531-532 ◽  
pp. 40-44
Author(s):  
Zhi Feng Liu ◽  
Yi Ting Liu
Keyword(s):  
Solar Cell ◽  
Current Density ◽  
Copper Phthalocyanine ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Energy Conversion Efficiency ◽  
Short Circuit Current Density ◽  
Hybrid Solar Cell ◽  
Photovoltaic Properties ◽  
Current Voltage

Hybrid solar cell based on copper-phthalocyanine (CuPc) and textured Si has been fabricated. Influence of silicon texturization on the photovoltaic properties of CuPc/n-Si hybrid solar cell was studied by current-voltage characteristic curves in the dark and under illumination conditions. As a result, it is found that textured Si can improve significantly the performance of hybrid solar cell. It exhibits a three times increase in the short-circuit current density with respect to that of the standard hybrid solar cell, and the short-circuit current density reaches up to 5.4 mA/cm2. In addition, the open-voltage and fill factor are almost constant. The solar-energy conversion efficiency is increased by about three times by the textured Si and achieved about 0.8% under “one Sun” illumination. Furthermore, the possible reasons for this result have been discussed.

scholarly journals Synthesis of Cyano-Substituted Conjugated Polymers for Photovoltaic Applications

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 746 ◽  
Author(s):  
Mun Ho Yang ◽  
Ho Cheol Jin ◽  
Joo Hyun Kim ◽  
Dong Wook Chang
Keyword(s):  
Conjugated Polymers ◽  
Molecular Orbital ◽  
Polymer Solar Cells ◽  
Short Circuit ◽  
Energy Levels ◽  
Coupling Reaction ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Strong Electron ◽  
Photovoltaic Properties

Three conjugated polymers, in which the electron-donating (D) 5-alkylthiophene-2-yl-substitued benzodithiophene was linked to three different electron-accepting (A) moieties, i.e., benzothiadiazole (BT), diphenylquinoxaline (DPQ), and dibenzophenazine (DBP) derivative via thiophene bridge, were synthesized using the Stille coupling reaction. In particular, the strong electron-withdrawing cyano (CN) group was incorporated into the A units BT, DPQ, and DBP to afford three D–A type target polymers PB–BTCN, PB–DPQCN, and PB–DBPCN, respectively. Owing to the significant contribution of the CN-substituent, these polymers exhibit not only low-lying energy levels of both the highest occupied molecular orbital and the lowest unoccupied molecular orbital, but also reduced bandgaps. Furthermore, to investigate the photovoltaic properties of polymers, inverted-type devices with the structure of ITO/ZnO/Polymer:PC71BM/MoO3/Ag were fabricated and analyzed. All the polymer solar cells based on the three cyano-substituted conjugated polymers showed high open-circuit voltages (Voc) greater than 0.89 V, and the highest power conversion efficiency of 4.59% was obtained from the device based on PB-BtCN with a Voc of 0.93 V, short-circuit current of 7.36 mA cm−2, and fill factor of 67.1%.

scholarly journals Structure and Photoelectrical Properties of Natural Photoactive Dyes for Solar Cells

2018 ◽  
Vol 8 (9) ◽  
pp. 1697 ◽  
Author(s):  
Qian Liu ◽  
Nan Gao ◽  
Dejiang Liu ◽  
Jinglin Liu ◽  
Yuanzuo Li
Keyword(s):  
Density Functional Theory ◽  
Solar Cells ◽  
Density Functional ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Natural Dyes ◽  
Functional Theory ◽  
Photoelectrical Properties

A series of natural photoactive dyes, named as D1–D6 were successfully extracted from six kinds of plant leaves for solar cells. The photoelectrical properties of dyes were measured via UV-Vis absorption spectra, cyclic voltammetry as well as photovoltaic measurement. To theoretically reveal the experimental phenomena, the chlorophyll was selected as the reference dye, where the ground and excited state properties of chlorophyll were calculated via density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The experimental results show that the absorption peaks of those dyes are mainly distributed in the visible light regions of 400–420 nm and 650–700 nm, which are consistent with the absorption spectrum of chlorophyll. The photoelectrical conversion efficiencies of the solar cells sensitized by the six kinds of natural dyes are in the order of D1 > D4 > D2 > D5 > D6 > D3. The dye D1 performance exhibits the highest photoelectrical conversion efficiency of 1.08% among the investigated six natural dyes, with an open circuit voltage of 0.58 V, a short-circuit current density of 2.64 mA cm−2 and a fill factor of 0.70.

scholarly journals Fabrication and Characterization of CH3NH3PbI3 Perovskite Solar Cells Added with Polysilanes

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Takeo Oku ◽  
Junya Nomura ◽  
Atsushi Suzuki ◽  
Hiroki Tanaka ◽  
Sakiko Fukunishi ◽  
...  
Keyword(s):  
Solar Cells ◽  
Short Circuit ◽  
Perovskite Solar Cells ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Interfacial Structure ◽  
Perovskite Layer ◽  
Photovoltaic Properties ◽  
Coating Method

Effects of polysilane additions on CH3NH3PbI3 perovskite solar cells were investigated. Photovoltaic cells were fabricated by a spin-coating method using perovskite precursor solutions with polymethyl phenylsilane, polyphenylsilane, or decaphenyl cyclopentasilane (DPPS), and the microstructures were examined by X-ray diffraction and optical microscopy. Open-circuit voltages were increased by introducing these polysilanes, and short-circuit current density was increased by the DPPS addition, which resulted in the improvement of the photoconversion efficiencies to 10.46%. The incident photon-to-current conversion efficiencies were also increased in the range of 400~750 nm. Microstructure analysis indicated the formation of a dense interfacial structure by grain growth and increase of surface coverage of the perovskite layer with DPPS, and the formation of PbI2 was suppressed, leading to the improvement of photovoltaic properties.

Effects of Deposition Parameters on the Structure and Photovoltaic Performance of Si Thin Films by Metal Induced Growth

2008 ◽  
Vol 1123 ◽  
Author(s):  
Peter T. Mersich ◽  
Shubhranshu Verma ◽  
Wayne A. Anderson ◽  
Rossman F. Giese
Keyword(s):  
Thin Films ◽  
Absorption Coefficient ◽  
Short Circuit ◽  
Photovoltaic Performance ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Photovoltaic Properties ◽  
X Ray ◽  
Metal Induced Growth

AbstractA metal-induced growth (MIG) process was employed to deposit thin films of microcrystalline silicon (μc-Si) for solar cell applications. Due to different grain orientations of the crystals, the absorption coefficient of μc-Si is about 10 times higher than the absorption coefficient of single crystalline Si. The properties of the Si film were investigated resulting from variations in several parameters. A range of Ni and Co thicknesses were examined from 7.5 nm to 60 nm including combinations of the two, while the dc sputtering power was stepped up from 150 W to 225 W. The structure of the resulting film was studied using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD). SEM of the film revealed that 5 hr of Si deposition at 150 W yields a film thickness of 6.5 μm and a maximum grain size of about 0.6 μm. EDS data showed that at the middle of the Si film the atomic percentage of the Si was 99.17%. XRD data showed that the dominant crystal orientation is {220}. To characterize the photovoltaic properties of the μc-Si, Schottky photodiodes were fabricated. Ni alone as the seed layer resulted in ohmic behavior. With Co only, MIG formed a rectifying contact with open-circuit voltage (V∝). The combination of Co layered over Ni formed better thin films and gave a Voc of 0.24 V and short-circuit current density (Jsc) of 5.0 mA/cm2 since the Co prevents Ni contamination of the top of the grown Si layer.

scholarly journals Multiferroic oxide BFCNT/BFCO heterojunction black silicon photovoltaic devices

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Kaixin Guo ◽  
Xu Wang ◽  
Rongfen Zhang ◽  
Zhao Fu ◽  
Liangyu Zhang ◽  
...  
Keyword(s):  
High Performance ◽  
Short Circuit ◽  
Double Perovskite ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Black Silicon ◽  
Photovoltaic Devices ◽  
Photovoltaic Properties ◽  
Carrier Separation

AbstractMultiferroics are being studied increasingly in applications of photovoltaic devices for the carrier separation driven by polarization and magnetization. In this work, textured black silicon photovoltaic devices are fabricated with Bi6Fe1.6Co0.2Ni0.2Ti3O18/Bi2FeCrO6 (BFCNT/BFCO) multiferroic heterojunction as an absorber and graphene as an anode. The structural and optical analyses showed that the bandgap of Aurivillius-typed BFCNT and double perovskite BFCO are 1.62 ± 0.04 eV and 1.74 ± 0.04 eV respectively, meeting the requirements for the active layer in solar cells. Under the simulated AM 1.5 G illumination, the black silicon photovoltaic devices delivered a photoconversion efficiency (η) of 3.9% with open-circuit voltage (Voc), short-circuit current density (Jsc), and fill factor (FF) of 0.75 V, 10.8 mA cm−2, and 48.3%, respectively. Analyses of modulation of an applied electric and magnetic field on the photovoltaic properties revealed that both polarization and magnetization of multiferroics play an important role in tuning the built-in electric field and the transport mechanisms of charge carriers, thus providing a new idea for the design of future high-performance multiferroic oxide photovoltaic devices.

scholarly journals Enhanced Performance of DSSCs Based on the Insertion Energy Level of CdS Quantum Dots

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaoping Zou ◽  
Zhe Sun
Keyword(s):  
Quantum Dots ◽  
Short Circuit ◽  
Energy Levels ◽  
Dye Sensitized Solar Cells ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Cds Quantum Dots ◽  
Visible Absorption ◽  
The Times

Cadmium sulfide (CdS) quantum dots (QDs) are assembled onto the TiO2films by chemical bath deposition method (CBD). And the QDs size is controlled by the times of CBD cycles. They are characterized by UV-visible absorption. To avoid the photo corrosion and electrolyte corrosion, CdS and N719 are sequentially assembled onto the nanocrystalline TiO2films to prepare a CdS/N719 cosensitized photo electrode for the dye-sensitized solar cells. In the structure of TiO2/CdS/N719 electrode, the reorganization of energy levels between CdS and N719 forms a stepwise structure of band-edge levels which is advantageous to the electron injection and hole recovery of CdS and N719 QDs. The open circuit voltage (Voc), short circuit current density (Jsc), and efficiency are increased.

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