Organic solar cells have obtained a prodigious amount of attention in photovoltaic research due to their unique features of light weight, low cost, eco-friendliness, and semitransparency. A rising ...trend in this field is the development of all-small-molecules organic solar cells (ASM-OSCs) due to their merits of excellent batch-to-batch reproducibility, well-defined structures, and simple purification. Among the numerous organic photovoltaic (OPV) materials, benzodithiophene (BDT)-based small molecules have come to the fore in achieving outstanding power conversion efficiency (PCE) and breaking the 17% efficiency barrier in single-junction OPV devices, indicating the significant potential of this class of materials in commercial photovoltaic applications. This review specially focuses on up-to-date information about improvements in BDT-based ASM-OSCs since 2011 and provides an outlook on the most significant challenges that remain in the field. We believe there will be more exciting BDT-based photovoltaic materials and devices developed in the near future.
Undoped and copper (Cu) doped zinc oxide (Zn
1−
x
Cu
x
O
, where
x
= 0-0.065) nano crystal thin films have been deposited on glass substrate via RF/DC reactive co-sputtering technique. The aim of ...this work is to investigate the crystal structure of ZnO and Cu doped ZnO thin films and also study the effect of Cu doping on optical band gap of ZnO thin films. The identification and confirmation of the crystallinity, film thickness and surface morphology of the nano range thin films are confirmed by using X-ray diffractometer (XRD), scanning electron microscope and atomic force microscope. The XRD peak at a diffractive angle of 34.44°and Miller indices at (002) confirms the ZnO thin films. Crystallite size of undoped ZnO thin films is 27 nm and decreases from 27 nm to 22 nm with increasing the atomic fraction of Cu (
x
Cu
) in the ZnO thin films from 0 to 6.5% respectively, which is calculated from XRD (002) peaks. The different bonding information of all deposited films was investigated by Fourier transform infrared spectrometer in the range of wave number between 400 cm
−1
to 4000 cm
−1
. Optical band gap energy of all deposited thin films was analyzed by ultraviolet visible spectrophotometer, which varies from 3.35 eV to 3.19 eV with the increase of
x
Cu
from 0 to 6.5% respectively. Urbach energy of the deposited thin films increases from 115 meV to 228 meV with the increase of
x
Cu
from 0to6.5% respectively.
The increasing energy demands of the global community can be met with solar energy. Solution-processed organic solar cells have seen great progress in power conversion efficiencies (PCEs). ...Semitransparent organic solar cells (ST-OSCs) have made enormous progress in recent years and have been considered one of the most promising solar cell technologies for applications in building-integrated windows, agricultural greenhouses, and wearable energy resources. Therefore, through the synergistic efforts of transparent electrodes, engineering in near-infrared photoabsorbent materials, and device engineering, high-performance ST-OSCs have developed, and PCE and average visible transmittance reach over 10% and 40%, respectively. In this review, we present the recent progress in photoabsorbent material engineering and strategies for enhancing the performance of ST-OSCs to help researchers gain a better understanding of structure-property-performance relationships. To conclude, new design concepts in material engineering and outlook are proposed to facilitate the further development of high-performance ST-OSCs.
A new and effective planar D-π-A configured small organic molecule (SOM) of 2-5-(3,5-dimethoxystyryl)thiophen-2-yl)methylene)-1H-indene-1,3(2H)-dione, abbreviated as DVB-T-ID, was synthesized using ...1,3-indanedione acceptor and dimethoxy vinylbenzene donor units, connected through a thiophene π-spacer. The presence of a dimethoxy vinylbenzene unit and π-spacer in DVB-T-ID significantly improved the absorption behavior by displaying maximum absorbance at ~515 nm, and the reasonable band gap was estimated as ~2.06 eV. The electronic properties revealed that DVB-T-ID SOMs exhibited promising HOMO (−5.32 eV) and LUMO (−3.26 eV). The synthesized DVB-T-ID SOM was utilized as donor material for fabricating solution-processed bulk heterojunction organic solar cells (BHJ-OSCs) and showed a reasonable power conversion efficiency (PCE) of ~3.1% with DVB-T-ID:PC61BM (1:2, w/w) active layer. The outcome of this work clearly reflects that synthesized DVB-T-ID based on 1,3-indanedione units is a promising absorber (donor) material for BHJ-OSCs.
In order to develop new and effective donor materials, a planar donor-π-acceptor (D-π-A) type small organic molecule (SOM), 2-(4-fluorobenzoyl)-3-(5″-hexyl-2,2′:5′,2″-terthiophen-5-yl) acrylonitrile, ...named as H3T-4-FOP, was synthesized by the reaction of 4-fluorobenzoylacetonitrile (as acceptor unit) and hexyl terthiophene (as donor unit) derivatives. Promising optical, solubility, electronic and photovoltaic properties were observed for the H3T-4-FOP SOM. Significantly, the presence of 4-fluorobenzoylacetonitrile as an acceptor unit in H3T-4-FOP SOM tuned the optical band gap to ~2.01 eV and procured the reasonable energy levels as highest occupied molecular orbital (HOMO) of −5.27 eV and lowest unoccupied molecular orbital (LUMO) −3.26 eV. The synthesized H3T-4-FOP SOM was applied as a donor material to fabricate solution-processed bulk heterojunction organic solar cells (BHJ-OSCs) with an active layer of H3T-4-FOP: PC61BM (1:2, w/w) and was validated as having a good power conversion efficiency (PCE) of ~4.38%. Our studies clearly inspire for future designing of multifunctional groups containing the 4-fluorobenzoylacetonitrile based SOM for high performance BHJ-OSCs.
Three conjugated copolymers, PDPP-2FTVT, PIID-2FTVT, and PNDI-2FTVT based on the 2,2′-(1E)-1,2-ethenediylbis3-fluorothiophene (2FTVT) core with varying acceptor units, diketopyrrolopyrrole (DPP), ...isoindigo (IID), and naphthalenediimide (NDI) were developed for organic field-effect transistors (OFETs). Combined electron-withdrawing fluorine atoms and vinyl linkage in the 2FTVT unit not only reduce the frontier molecular orbital energies but also extended the absorption profile and planarize the polymer backbone, manifesting synergetic effect on the strengthened molecular interactions and charge-carrier properties. The resulted copolymer, PDPP-2FTVT show highly reliable thin film transistor properties with highest hole mobility of 1.93 cm2 V−1 s−1 compared to PIID-2FTV and PNDI-2FTVT. PIID-2FTV copolymer show ambipolar characteristic with hole and electron mobilities of 0.71 and 0.03 cm2 V−1 s−1 respectively while PNDI-2FTVT exhibited the highest electron mobility of 0.20 cm2 V−1 s−1 among three copolymers. Thin film micro-structure characterization reveal that the three copolymers formed lamellar, edge-on molecular packing (for PDPP-2FTVT and PIID-2FTV), increased crystallinity with smaller π-π stacking distances, and strengthen the planarity after thermal annealing. These results contribute important progresses in solution-processed OFET and could provide a greater possibility of 2FTVT based copolymers for commercial application.
Display omitted
•Three conjugated 2FTVT donor-based copolymers were designed and synthesized.•The impact of various acceptors on their OFET properties was fully discussed.•An excellent hole mobility of 1.93 cm2 V−1 s−1 was achieved for PDPP-2FTVT.•The work promotes future fluorinated 2FTVT-based materials for OFETs.
Solution-processed organic solar cells (OSCs) have great promise for next-generation solar energy conversion technologies. Innovative acceptors are constantly being designed to improve device ...efficiency. In this work, we designed and synthesized a series of A–π–D–π–A type non-fullerene acceptor (NFA) molecules, named IB-TOT, IB-TOM, IB-IOO, and IB-IOM for their applications in OSCs. All molecules showed high thermal stability, broad photoabsorption, and relatively lower highest occupied molecular orbital (HOMO) energy levels from −5.48 eV to −5.58 eV. The optimized OSCs based on these NFAs and PTB7-Th donor deliver power conversion efficiencies (PCEs) of 8.19%, 5.50%, 2.42%, and 3.10% for IB-TOT, IB-TOM, IB-IOO, and IB-IOM molecules, respectively. The higher PCE of IB-TOT-based OSCs is attributed to their excellent miscibility and superior interpenetrating network morphology compared to the other three compounds. These results demonstrate that using the 3-ethylrhodanine acceptor unit to construct the NFA molecule is a successful approach for outstanding achievement in OSCs.
•Four IDT-based NFA molecules were designed and synthesized.•The impact of various end-groups on device performance was fully discussed.•An empirical relationship between the end groups was established.•The best-performing OSCs achieved a maximum PCE of 8.19%.•The work promotes future OSC performance enhancement.
•An energetic indandione based D-π-A planar molecule, H3T-ID is synthesized.•H3T-ID is applied as donor material for bulk-heterojunction organic solar cells (BJH-OSCs)•BHJ-OSC fabricated with ...H3T-ID:PC61BM (1:2, w/w) displays maximum PCE = ~4.05%•H3T-ID donor drives the reproducible and highly stable fabricated BHJ-OSCs.
The present work documents the synthesis of a new and highly energetic indandione based D-π-A planar molecule, 2-(5″-hexyl-2,2′:5′2″ terthiophen-5-yl) methylene)-1H- indene-1,3(2H) dione, H3T-ID), as donor material for bulk-heterojunction organic solar cells (BJH-OSCs). The photophysical properties, optoelectrical characterization and microscopic images were thoroughly studied. H3T-ID exhibited good absorption behavior with maximum absorbance at ~495 nm and displayed the optical band gap of ~1.98 eV. The existence of π-spacer and hexyl side chain in H3T-ID significantly improved the thin film morphology, molecular packing and enhanced the charge transport. H3T-ID organic molecule acquired well-matched HOMO and bountifully higher LUMO energy levels w.r.t. PC61BM acceptor. The photovoltaic characteristics of the fabricated BHJ-OSC using H3T-ID as donor and PC61BM as acceptor displayed maximum PCE = ~4.05%, good JSC = ~10.43 mAcm−2, VOC = ~0.77 V and FF = 0.51. The stability test revealed that the fabricated BHJ-OSCs showed good reproducibility and stability by retaining over ~80% of its initial PCE for 15 days without encapsulation.
In today’s era of technology, especially in the Internet commerce and banking, the transactions done by the Mastercards have been increasing rapidly. The card becomes the highly useable equipment for ...Internet shopping. Such demanding and inflation rate causes a considerable damage and enhancement in fraud cases also. It is very much necessary to stop the fraud transactions because it impacts on financial conditions over time the anomaly detection is having some important application to detect the fraud detection. A novel framework which integrates Spark with a deep learning approach is proposed in this work. This work also implements different machine learning techniques for detection of fraudulent like random forest, SVM, logistic regression, decision tree, and KNN. Comparative analysis is done by using various parameters. More than 96% accuracy was obtained for both training and testing datasets. The existing system like Cardwatch, web service-based fraud detection, needs labelled data for both genuine and fraudulent transactions. New frauds cannot be found in these existing techniques. The dataset which is used contains transaction made by credit cards in September 2013 by cardholders of Europe. The dataset contains the transactions occurred in 2 days, in which there are 492 fraud transactions out of 284,807 which is 0.172% of all transaction.
To determine the source of drinking water and to assess its relationship with the frequency of diarrhoea among households of Nurpur Shahan.
A cross-sectional descriptive study was carried out in ...January 2010 with a preformed questionnaire. Systematic random sampling was used to collect data. Participants' consent was obtained and confidentiality was maintained during the survey and during analysis. Households were evaluated for the frequency of diarrhoea in relation to their water source, its purification, and availability of sanitation facilities. All collected data was analyzed using SPSS 10.0.
Of the 107 households surveyed, 2.8% used wells, 63% used tap water and 32.7% used hand pumps, whereas only 0.9% consumed store-bought water as their major source of drinking water. The difference in the frequency of diarrhoea between those households who purified their water and those that did not was just 1%. The relationship between the source of drinking water and the frequency of diarrhoea was not statistically significant (p = 0.319). Surprisingly households with no disposal facilities only had a 20% frequency of diarrhoea; this was found to be statistically significant (p = 0.023).
This study contradicts the general conception that water supply is responsible for diarrhoea in the locality of Nurpur Shahan; it was found that the statistical difference between diarrhoea resulting from purified and non purified water was very small (p-value=0.587). Rather, improper sanitation and poor personal hygiene seem largely responsible for diarrhoea in this rural Islamabad community.
PDF
