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Effects of HTL and ETL Thicknesses on the Performance of PQT-12/PCDTBT:PC61BM/ZnO QDs Solar Cells
摘要： In this letter, floating film transfer method (FTM) based poly (3, 3'''- dialkylquaterthiophene) (PQT-12) hole transfer layer (HTL) has been explored for the performance improvement of poly[N-9’-heptadecanyl-2,7-carbazole-alt-5,5-(4’,7’-di-2-thienyl-2’, 1’, 3’-benzothiadiazole)]:[6,6]-phenyl-C61butyric acid methyl ester (PCDTBT:PC61BM) based bulk heterojunction (BHJ) solar cells. The BHJ is formed by sandwiching PCDTBT:PC61BM between FTM coated PQT-12 HTL and spin-coated ZnO quantum dots (QDs) electron transport layer (ETL). The better phase matching of FTM deposited PQT-12 HTL to the PCDTBT:PC61BM based blend polymeric active layer along with the visible absorption spectrum of the PQT-12 enhances the energy harvesting capability of the solar cell structure. The solar cell performance parameters such as the open circuit voltage (VOC), short circuit current density (JSC), fill factor (FF) and power conversion efficiency (PCE) are investigated for ~20 to 60 nm thin PQT-12 and ~20 to 35 nm thin ZnO films. The obtained VOC, JSC, FF, and PCE are 0.672 V, 10.42 mA/cm2, 38%, and 2.66%, respectively for ~20 nm PQT-12 and ~35 nm ZnO QDs.
关键词： PCDTBT,PQT-12,Floating film transfer method (FTM),Solar Cells,Bulk heterojunction
更新于2025-09-23 15:21:01
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DFT and TD-DFT studies of new pentacene-based organic molecules as a donor material for bulk-heterojunction solar cells
摘要： The performance of organic cells based on bulk heterojunctions (BHJs) has improved recently, but further improvements are necessary. In this work, we have carried out a thorough examination using density functional theory (DFT) and time-dependent (TD)-DFT to investigate the structural and optoelectronic properties of pentacene-based organic molecules (PbOMs) as potential donor material for organic photovoltaic BHJ devices. Our results show that oxadiazole prefers to attach via its nitrogen atoms to the carbon atoms of the pentacene monomer with an adsorption energy about ? 32.86 kcal/mol, which means that oxadiazole is efficiently adsorbed on the edge of the pentacene. The HOMO energy level of the PbOM with the lowest bandgap is ? 4.00 eV wide, i.e., about 0.86 eV lower and more positive than pentacene, thus providing an ideal open-circuit voltage for photovoltaic devices. The bandgap of the PbOM compounds are about 1.61 and 1.80 eV affording an efficient charge transfer from donor to acceptor. Furthermore, the donor PbOMs are also more stable than the pentacene. We have examined, additionally, the reactivity and absorption properties of individual molecules and PbOM systems. Our results suggest that the PbOM, as a donor material, may significantly improve the efficiency of BHJ solar cells.
关键词： TD-DFT,Pentacene,Bulk-heterojunction,Donor material
更新于2025-09-23 15:21:01
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Tackling Performance Challenges in Organic Photovoltaics: An Overview about Compatibilizers
摘要： Organic Photovoltaics (OPVs) based on Bulk Heterojunction (BHJ) blends are a mature technology. Having started their intensive development two decades ago, their low cost, processability and flexibility rapidly funneled the interest of the scientific community, searching for new solutions to expand solar photovoltaics market and promote sustainable development. However, their robust implementation is hampered by some issues, concerning the choice of the donor/acceptor materials, the device thermal/photo-stability, and, last but not least, their morphology. Indeed, the morphological profile of BHJs has a strong impact over charge generation, collection, and recombination processes; control over nano/microstructural morphology would be desirable, aiming at finely tuning the device performance and overcoming those previously mentioned critical issues. The employ of compatibilizers has emerged as a promising, economically sustainable, and widely applicable approach for the donor/acceptor interface (D/A-I) optimization. Thus, improvements in the global performance of the devices can be achieved without making use of more complex architectures. Even though several materials have been deeply documented and reported as effective compatibilizing agents, scientific reports are quite fragmentary. Here we would like to offer a panoramic overview of the literature on compatibilizers, focusing on the progression documented in the last decade.
关键词： mixing interfaces,additives,bulk heterojunction,morphology modulators,donor/acceptor interface,organic photovoltaics,compatibilizers
更新于2025-09-23 15:21:01
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An inverted BiI3/PCBM binary quasi-bulk heterojunction solar cell with a power conversion efficiency of 1.50%
摘要： The use of toxic Pb hinders the widespread applications of lead halide perovskite solar cells, sparking an upsurge effort to develop lead-free solar cells. This work reports a facile low-temperature solution processed bismuth triiodide (BiI3)/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) binary quasi-bulk heterojunction (BQ-BH) solar cell. The BiI3 and PCBM layers are innovatively utilized as the electron donor and acceptor to form a BQ-BH that promotes the separation of the excitons. The effective separation of excitons at the BiI3/PCBM BQ-BH is experimentally confirmed by the Kelvin probe force microscopy. An optimized inverted BiI3/PCBM BQ-BH solar cell can achieve a champion power conversion efficiency of 1.50% with a record short-circuit current density of 8.76 mA cm-2. The findings of this work confirm that the separation of excitons can be effectively promoted by inducing a suitable electron donor/acceptor type of BQ-BH, providing a new means to enhance the performance of BiI3-based solar cells.
关键词： electron acceptor,quasi-bulk heterojunction,exciton separation,solar cells,BiI3
更新于2025-09-23 15:21:01
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Theoretical study of new conjugated compounds with a low bandgap for bulk heterojunction solar cells: DFT and TD-DFT study
摘要： Bulk heterojunction solar cells have attracted scientific and economic interest in recent years, and have just been one of the future photovoltaic technologies to produce energy at low cost. To study the electronic and geometric properties of a novel conjugated polymer called r-PTTDPP50, which is formed from a derivative of diketopyrrolopyrrole (DPP), thiophene conjugated side chain and 2, 5-bis (trimethylstannyl) thiophene, functional density theory (DFT) has been used with several methods such as B3LYP, PBEPBE, B3PW91 and mPW1PW91 and the basis set 6-31G (d, p),to obtain the most appropriate method. The absorption properties have been obtained by the CAM-B3LYP method. Then, the functional tests giving the closest result to the experimental ones will be used to propose other structure candidates for applications in the domain of organic electronics. This research has been used to conduct next syntheses to compounds more helpful as active materials in optoelectronic.
关键词： Bulk heterojunction,DFT,solar cells,diketopyrrolopyrrole (DPP),thiophene
更新于2025-09-23 15:21:01
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Utility of copper oxide nanoparticles (CuO-NPs) as efficient electron donor material in bulk-heterojunction solar cells with enhanced power conversion efficiency
摘要： In the present work, we have endeavored the utilization of wet-chemically synthesized copper oxide nanoparticles (CuO-NPs) as the active layer in hybrid bulk heterojunction (BHJ) solar cells. The BHJs with CuO-NPs display significantly different physics from customary BHJs, and prove a noteworthy improvement in their performance. It is noted that with the addition of CuO-NPs, the morphology of the photoactive layer endures significant changes. Incorporating CuO-NPs is an additional paradigm for BHJs solar cells which enhances the photocurrent density from 9.43 mA/cm2 to 11.32 mA/cm2 and the external quantum efficiency as well. Also the power-conversion efficiency (PCE) improved from 2.85 % to 3.82 % without harming the open circuit voltage and the fill factor. The enhancement in PCE achieved here makes it worthy to design high-performance organic solar cells holding inorganic nanoparticles.
关键词： thin films,Bulk heterojunction,Solar cells,external quantum efficiency,Copper oxide nanoparticles,photo current density
更新于2025-09-23 15:19:57
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Measurement and Theoretical Interpretation of Exciton Diffusion as a Function of Intermolecular Separation for Squaraines Targeted for Bulk Heterojunction Solar Cells
摘要： The efficiency of bulk heterojunction (BHJ) organic photovoltaic (OPV) devices depends significantly upon absorption of photons and the migration of the photogenerated excited state to the heterojunction interface between the electron donor and electron acceptor. Within anilino-squaraine, molecules known for their successful use in the active layer of OPV devices, electronic aggregation strongly influences the absorption spectrum, energy transfer (EnT), and exciton migration to this heterojunction interface. Therefore, the long-range transition dipole coupling and the relative populations of the associated excited states dictate the general effectiveness of these materials in optoelectronic devices. This work presents subpicosecond transient absorption (TA) data that probe the excited-state photophysics of samples with a continuum of intermolecular separation, from monomers in solution to high-concentration solid solution thin films analogous to OPV active layers. EnT times are calculated for each squaraine concentration, and pump-power dependence provides evidence for significant EnT despite a high preponderance of H-aggregation. Theoretical modeling of essential states supports the interpretation from TA spectra that excited states relax into more tightly packed H-aggregates. This work prompts further questions regarding a far-reaching mechanistic EnT bottleneck for molecular and polymeric BHJ devices.
关键词： H-aggregation,squaraine,organic photovoltaic,bulk heterojunction,exciton diffusion,energy transfer
更新于2025-09-23 15:19:57
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Understanding the Performance of Organic Photovoltaics under Indoor and Outdoor Conditions: Effects of Chlorination of Donor Polymers
摘要： Understanding the effects of the chemical structures of donor polymers on the photovoltaic properties of their corresponding organic photovoltaic (OPV) devices under various light-intensity conditions is important for improving the performance of these devices. We synthesized a series of copolymers based on poly[(2,6-(4,8-bis(5-(2-thioethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione)] (PBDB-TS) and studied the effects of chlorine substitution of its thiophene-substituted benzodithiophene (BDT-Th) unit on its photovoltaic properties. The chlorination of the polymer resulted in a bulk heterojunction (BHJ) morphology optimized for efficient charge transport with suppressed leakage current and an increased open-circuit voltage of the OPV device; this optimization led to a remarkable enhancement of the OPV device’s power conversion efficiency (PCE) not only under the condition of 1 sun illumination but also under the condition of low light intensity mimicking indoor light; the PCE increased from 8.7% for PBDB-TS to ~13% for the chlorinated polymers, PBDT-TS-3Cl and PBDT-TS-4Cl, under the 1 sun illumination condition and from 5.3% for PBDB-TS to 21.7% for PBDB-TS-4Cl under 500 lx fluorescence illuminance. Interestingly, although the OPV PCEs under 1 sun illumination were independent of the position of chlorine substitution onto the polymer, the PBDB-TS-4Cl exhibited better performance under simulated indoor light than its derivative PBDB-TS-3Cl. Our results demonstrate that efficient light absorption and charge-carrier generation play key roles in achieving high OPV efficiency under low-light-intensity conditions.
关键词： bulk heterojunction,benzodithiophene,indoor light,chlorine substitution,organic photovoltaic
更新于2025-09-23 15:19:57
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In situ Measuring Film-Depth-Dependent Light Absorption Spectra for Organic Photovoltaics
摘要： Organic donor–acceptor bulk heterojunction are attracting wide interests for solar cell applications due to solution processability, mechanical ?exibility, and low cost. The photovoltaic performance of such thin ?lm is strongly dependent on vertical phase separation of each component. Although ?lm-depth-dependent light absorption spectra measured by non-in situ methods have been used to investigate the ?lm-depth pro?ling of organic semiconducting thin ?lms, the in situ measurement is still not well-resolved. In this work, we propose an in situ measurement method in combination with a self-developed in situ instrument, which integrates a capacitive coupled plasma generator, a light source, and a spectrometer. This in situ method and instrument are easily accessible and easily equipped in laboratories of the organic electronics, which could be used to conveniently investigate the ?lm-depth-dependent optical and electronic properties.
关键词： light absorption,bulk heterojunction,spectroscopy,organic solar cells,depth pro?ling,organic photovoltaics
更新于2025-09-23 15:19:57
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Effect of PQT-12 interface layer on the performance of PCDTBT: PCBM bulk heterojunction solar cells
摘要： The effect of PQT-12 interface layer on the performance of PCDTBT:PCBM based bulk heterojunction (BHJ) organic solar cells (OSCs) is reported in this paper. The PQT-12 interface layer is obtained by cost and material effective technique, floating film transfer method (FTM). It is shown that the use of FTM-based PQT-12 HTL significant improves the power conversion efficiency (PCE) and external quantum efficiency (EQE) of the OSCs over only PEDOT:PSS HTL based OSCs. The OSC has the maximum values of JSC (=5.62 mA cm?2), VOC (=562 mV) and FF (=0.33) in the PQT-12 incorporated structure due to efficient carrier transfer at the interface. The PCE of nearly twice of the only PEDOT:PSS HTL OSC is obtained in case of the PQT-12/PEDOT:PSS structure.
关键词： organic solar cell (OSC),PCDTBT,bulk heterojunction,PQT-12,floating film transfer method (FTM)
更新于2025-09-23 15:19:57