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 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.

scholarly journals Steady Enhancement in Photovoltaic Properties of Fluorine Functionalized Quinoxaline-Based Narrow Bandgap Polymer

Molecules ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 54 ◽  
Author(s):  
Zhonglian Wu ◽  
Huanxiang Jiang ◽  
Xingzhu Wang ◽  
Lei Yan ◽  
Wei Zeng ◽  
...  
Keyword(s):  
Fill Factor ◽  
Polymer Solar Cells ◽  
Short Circuit ◽  
Photovoltaic Performance ◽  
Hole Mobility ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Promising Candidate ◽  
Photovoltaic Properties ◽  
Narrow Bandgap

To investigate the influence of fluoride phenyl side-chains onto a quinoxaline (Qx) unit on the photovoltaic performance of the narrow bandgap (NBG) photovoltaic polymers, herein, two novel NBG copolymers, PBDTT-DTQx and PBDTT-DTmFQx, were synthesized and characterized. 2-ethylhexylthiothiophene-substituted benzodithiophene (BDTT), 2,3-diphenylquinoxaline (DQx) [or 2,3-bis(3-fluorophenyl)quinoxaline (DmFQx)] and 2-ethylhexylthiophene (T) were used as the electron donor (D) unit, electron-withdrawing acceptor (A) unit and π-bridge, respectively. Compared to non-fluorine substituted PBDTT-DTQx, fluoride PBDTT-DTmFQx exhibited a wide UV-Vis absorption spectrum and high hole mobility. An enhanced short-circuit current (Jsc) and fill factor (FF) simultaneously gave rise to favorable efficiencies in the polymer/PC71BM-based polymer solar cells (PSCs). Under the illumination of AM 1.5G (100 mW cm−2), a maximum power conversion efficiency (PCE) of 6.40% was achieved with an open-circuit voltage (Voc) of 0.87 V, a Jsc of 12.0 mA cm−2 and a FF of 61.45% in PBDTT-DTmFQx/PC71BM-based PSCs, while PBDTT-DTQx-based devices also exhibited a PCE of 5.43%. The excellent results obtained demonstrate that PBDTT-DTmFQx by fluorine atom engineering could be a promising candidate for organic photovoltaics.

An efficient method to achieve a balanced open circuit voltage and short circuit current density in polymer solar cells

2016 ◽  
Vol 4 (21) ◽  
pp. 8291-8297 ◽  
Author(s):  
Dongfeng Dang ◽  
Pei Zhou ◽  
Linrui Duan ◽  
Xichang Bao ◽  
Renqiang Yang ◽  
...  
Keyword(s):  
Solar Cells ◽  
Current Density ◽  
Efficient Method ◽  
Open Circuit Voltage ◽  
Polymer Solar Cells ◽  
Short Circuit ◽  
Energy Levels ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit

Good light harvesting properties and matched energy levels as well as enhanced Jsc value and high Voc value in solar cells were achieved simultaneously by construction of the D–A–π–A type regular terpolymers of PIDT-DTQ-TT, finally leading to the maximum PCE value of 6.63% in PSCs.

The Side-Chain Effects on Photovoltaic Properties of Copolymers Based on Phenothiazine and Thiophene

2013 ◽  
Vol 634-638 ◽  
pp. 2621-2628 ◽  
Author(s):  
Han Sol Yoo ◽  
Dae Hee Yun ◽  
Tae Won Ko ◽  
Yong Sung Park ◽  
Je Wan Woo
Keyword(s):  
Fill Factor ◽  
Optical Band Gap ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Coupling Reaction ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Side Chain ◽  
Photovoltaic Properties ◽  
Suzuki Coupling Reaction

In this study, the alternating conductive polymers based on phenothiazine and bithiophene unit, poly[(N-10-dodecyl-phenothiazin-3,7-ylene)-alt-(2,2’-bithiophen-5-yl)] (P1) and poly[(N-10- dodecyl-phenothiazin-3,7-ylene)-alt-(4,4’-didodecyl-2,2’-bithiophen-5-yl)] (P2), were synthesized by Suzuki coupling reaction in the presence of palladium catalyst. The structures of synthesized compounds were confirmed by 1H NMR. The optical, electrochemical properties of synthesized polymers were investigated by UV-Vis, cyclic voltammetry (CV). The optical band gap of 2.22 eV and 2.50 eV was obtained from absorption onset of UV-Vis spectrum. Then, the two devices using blends of the polymer, as a donor, and PC71BM, as an acceptor, were fabricated by spin-coating. The device with a P1:PC71BM (1:4, w/w) as an active layer exhibited the best performance with an open circuit voltage (VOC) of 0.68 V, short circuit current (JSC) of 3.5 mA/cm2, fill factor (FF) of 31.8 % and power conversion efficiency (PCE) of 0.74 %.

scholarly journals Efficient Solar Cells Based on a Polymer Donor with β-Branching in Trialkylsilyl Side Chains

2021 ◽  
Vol 03 (02) ◽  
pp. 134-140
Author(s):  
Haijun Bin ◽  
Martijn M. Wienk ◽  
René A. J. Janssen
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Short Circuit ◽  
Energy Levels ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Side Chains ◽  
Photovoltaic Properties ◽  
Alkyl Groups ◽  
High Efficient

Side-chain engineering is an important strategy in designing novel polymer semiconductor materials for high-efficient organic solar cells. The use of trialkylsilyl side chains can improve the photovoltaic efficiency by decreasing the energy of the HOMO of the polymer and improving its crystallinity and hole mobility. Compared to simple linear derivatives, α-branching in the alkyl groups of trialkylsilyl side chains causes strong aggregation and excessive phase separation in the photoactive layer, leading to poor device performance. β-Branching of the alkyl groups has not yet been used in trialkylsilyl side chains. Herein, we describe a new polymer (J77) with triisobutylsilyl side chains to investigate the effect of β-branching on the molecular aggregation, optical properties, energy levels, and photovoltaic properties. We find that compared to α-branching, β-branching of alkyl groups in trialkylsilyl side chains significantly reduces aggregation. This enables J77 to form blend morphologies in films that provide high-efficient solar cells in combination with different non-fullerene acceptors. Moreover β-branching of the alkyl groups in trialkylsilyl side chains lowers the HOMO energy level of J77 and increases the open-circuit voltage of J77-based solar cells without sacrificing short-circuit current density or fill factor.

Constructing PbS quantum dot sensitized ZnO nanorod array photoelectrodes for highly efficient photovoltaic devices

2016 ◽  
Vol 94 (7) ◽  
pp. 687-692
Author(s):  
Masood Mehrabian ◽  
Naser Ghasemian
Keyword(s):  
Quantum Dot ◽  
Short Circuit ◽  
Zno Nanorods ◽  
Growth Period ◽  
Short Circuit Current ◽  
Nanorod Array ◽  
Open Circuit ◽  
Zno Film ◽  
Photovoltaic Properties ◽  
Pbs Quantum Dot

Solar cells with ZnO film/ZnO nanorods (NRs)/PbS quantum dot (QD) photoelectrodes were constructed and various properties were studied. The ZnO NRs were grown for different periods varying from 0 (ZnO film) to 30 min (ZnO NR30) and the effect of growth period on the photovoltaic properties was investigated. The cell with ZnO film/PbS QD as photoelectrode showed the open circuit voltage VOC of 0.59 V, short circuit current density JSC of 10.06 mAcm−2, and the power conversion efficiency of 3.29% under one sun illumination (air mass 1.5 global illumination at 100 mWcm−2). In a device containing of ZnO film/ZnO NR10/PbS QD (as photoelectrode), mentioned photovoltaic parameters increased to 0.61 V, 10.47 mAcm−2 and 3.81%, respectively.

scholarly journals Direct AFM-based nanoscale mapping and tomography of open-circuit voltages for photovoltaics

2018 ◽  
Vol 9 ◽  
pp. 1802-1808 ◽  
Author(s):  
Katherine Atamanuk ◽  
Justin Luria ◽  
Bryan D Huey
Keyword(s):  
Solar Cells ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Photovoltaic Performance ◽  
Three Dimensional ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Photovoltaic Properties ◽  
Order Of Magnitude ◽  
Individual Grains

The nanoscale optoelectronic properties of materials can be especially important for polycrystalline photovoltaics including many sensor and solar cell designs. For thin film solar cells such as CdTe, the open-circuit voltage and short-circuit current are especially critical performance indicators, often varying between and even within individual grains. A new method for directly mapping the open-circuit voltage leverages photo-conducting AFM, along with an additional proportional-integral-derivative feedback loop configured to maintain open-circuit conditions while scanning. Alternating with short-circuit current mapping efficiently provides complementary insight into the highly microstructurally sensitive local and ensemble photovoltaic performance. Furthermore, direct open-circuit voltage mapping is compatible with tomographic AFM, which additionally leverages gradual nanoscale milling by the AFM probe essentially for serial sectioning. The two-dimensional and three-dimensional results for CdTe solar cells during in situ illumination reveal local to mesoscale contributions to PV performance based on the order of magnitude variations in photovoltaic properties with distinct grains, at grain boundaries, and for sub-granular planar defects.

Photovoltaic properties of silicon nanocrystals in silicon nitride prepared by ammonia sputtering

2015 ◽  
Vol 08 (05) ◽  
pp. 1550052
Author(s):  
Xiaobo Chen
Keyword(s):  
Silicon Nitride ◽  
Flow Rate ◽  
Photoelectron Spectroscopy ◽  
Silicon Nanocrystals ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Photovoltaic Properties ◽  
X Ray ◽  
Xps Characterization

In this work, we present an investigation of the photovoltaic properties of low-temperature (700°C annealing temperature) prepared P -doped Silicon nanocrystals ( Si   NCs ) in silicon nitride by ammonia sputtering followed by rapid thermal annealing (RTA). We examined how the flow rate of NH3influenced the structural properties of the annealed films by using Raman scattering, grazing incidence X-ray diffraction (GI XRD) and transmission electron microscopy (TEM), it was found that the appropriate flow rate of NH3is 3 sccm. For the sample deposited at the flow rate of 3 sccm, TEM image showed that Si   NCs were formed with a mean size about 3.7 nm and the density of ~ 2.1 × 1012cm-2; X-ray photoelectron spectroscopy (XPS) characterization showed the existence of Si – P bonds, indicating effective P doping; the average absorptance of higher than 65% and a significant amount of photocurrent makes it suitable for photoactive. Moreover, the experimental P -doped Si   NCs : Si3N4/ p - Si heterojunction solar cell has been fabricated, and the device performance was studied. The photovoltaic device fabricated exhibits an open-circuit voltage (VOC) and a short-circuit current density (JSC) of 470 mV and 3.25 mA/cm2, respectively.

A naphthodithiophene-based nonfullerene acceptor for high-performance polymer solar cells with a small energy loss

2020 ◽  
Vol 8 (19) ◽  
pp. 6513-6520 ◽  
Author(s):  
Xingliang Dong ◽  
Qing Guo ◽  
Qi Liu ◽  
Lei Zhu ◽  
Xia Guo ◽  
...  
Keyword(s):  
High Performance ◽  
Open Circuit Voltage ◽  
Polymer Solar Cells ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Small Energy ◽  
High Performance Polymer ◽  
Nonfullerene Acceptor

A new non-fullerene acceptor named NTO-4F is developed. The optimal PSC based on PM6:NTO-4F achieves a PCE of 11.5% with simultaneously high open-circuit voltage of 0.99 V and short-circuit current density of 19.1 mA cm−2.

scholarly journals Donor-Acceptor Polymer Based on Planar Structure of Alkylidene-Fluorene Derivative: Correlation of Power Conversion Efficiency among Polymer and Various Acceptor Units

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2859
Author(s):  
Eui Jin Lee ◽  
Ho Jun Song
Keyword(s):  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Short Circuit ◽  
Power Conversion ◽  
Average Molecular Weight ◽  
Coupling Reaction ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Planar Structure ◽  
Quinoxaline Derivatives

This study synthesized a novel polymer, poly(alkylidene fluorene-alt-diphenylquinoxaline) (PAFDQ), based on a planar alkylidene-fluorene and a highly soluble quinoxaline derivative through the Suzuki coupling reaction. We designed a novel molecular structure based on alkylidene fluorene and quinoxaline derivatives due to compact packing property by the planar structure of alkyidene fluorene and efficient intra-molecular charge transfer by quinoxaline derivatives. The polymer was largely dissolved in organic solvents, with a number average molecular weight and polydispersity index of 13.2 kg/mol and 2.74, respectively. PAFDQ showed higher thermal stability compared with the general fluorene structure owing to its rigid alkylidene-fluorene structure. The highest occupied and lowest unoccupied molecular orbital levels of PAFDQ were −5.37 eV and −3.42 eV, respectively. According to X-ray diffraction measurements, PAFDQ exhibited the formation of an ordered lamellar structure and conventional edge-on π-stacking. The device based on PAFDQ/Y6-BO-4Cl showed the best performance in terms of short circuit current (9.86 mA/cm2), open-circuit voltage (0.76 V), fill factor (44.23%), and power conversion efficiency (3.32%). Moreover, in the PAFDQ/Y6-BO-4Cl-based film, the phase separation of donor-rich and acceptor-rich phases, and the connected dark domains, was observed.

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