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Modulated charge transport characteristics in solution-processed UV photodetector by incorporating localized built-in electric field
摘要： The application of ZnO in the field of ultraviolet (UV) photodetectors is hindered by the lower responsivity, which is attributed to the strong band-to-band direct recombination caused by its large exciton binding energy and defect-assisted charge recombination related with the presence of defect states. Here, a solution-processed ZnO:Poly[N-90-heptadecanyl-2,7- carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)] (PCDTBT) composite photosensitive layer is employed to overcome these shortcomings. By incorporating PCDTBT, the localized built-in electric field can be constructed, which effectively facilitates the photogenerated exciton dissociation in annealing-free ZnO layer. Meanwhile, the formed depletion region in dark reduces the majority carrier density, thus decreasing the dark current of the photodetector. Furthermore, the absorption spectrum of PCDTBT perfectly overlaps the photoluminescence of ZnO, which is beneficial for the reutilization of carrier recombination energy by fluorescence resonance energy transfer. This study reveals that the charge recombination loss in ZnO limits the photoresponse, and points a direction to improve the light detection capacity of UV photodetectors.
关键词： ZnO,UV photodetector,Solution-processed,PCDTBT,Built-in electric field
更新于2025-11-14 15:27:09
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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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[IEEE 2019 12th International Conference on Developments in eSystems Engineering (DeSE) - Kazan, Russia (2019.10.7-2019.10.10)] 2019 12th International Conference on Developments in eSystems Engineering (DeSE) - The Effects of Al-Doped ZnO Layer on the Performance of Organic Solar Cell
摘要： The interface properties as well as the solar cell properties of inverted organic solar cells based on PCDTBT:PCBM blends were investigated using sol-gel aluminum doped ZnO as electron transport layers. The effects of Al concentration on the optical, structural and morphological properties of AZO layer were investigated. The results indicate that Al concentration has influenced the grain size growth leading to different surface morphology. High doping concentration resulted in higher charge carrier density and wider band gap. Using AZO layers in organic solar cell has increased their performance; the best performance was observed for the device with 0.5% Al-doped ZnO layer with efficiency of 3.24%, short circuit current density of 8.82mA.cm-2, fill factor of 0.46% and open circuit voltage of 0.81V, whereas the reference device has exhibited an efficiency of 2.9%, short circuit current density of 7.6mA.cm-2, fill factor of 0.48 % and open circuit voltage of 0.785V.
关键词： Electron Transport layer,PCDTBT:PCBM,Organic solar cell,AZO thin films
更新于2025-09-23 15:21:01
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Geminate recombination in organic photovoltaic blend PCDTBT/PC <sub/>71</sub> BM studied by out-of-phase electron spin echo spectroscopy
摘要： The key process in organic solar cell operation is charge separation under light illumination. Due to the low dielectric constant of organic materials, the Coulomb attraction energy within the interfacial charge-transfer state (CTS) is larger than the thermal energy. Understanding the mechanism of charge separation at the organic donor/acceptor interface still remains a challenge and requires knowledge of the CTS temporal evolution. To address this problem, the CTS in the benchmark photovoltaic blend PCDTBT/PC71BM was studied by the out-of-phase Electron Spin Echo (ESE). The protocol for determining the CTS geminate recombination rate for certain electron-hole distances was developed. Simulating the out-of-phase ESE trace for the CTS in the PCDTBT/PC71BM blend allows precise determination of the electron-hole distance distribution function and its evolution with the increase in the delay after the laser flash. Distances of charge separation up to 6 nm were detected upon thermalization at a temperature of 20 K. Assuming the exponential decay of the recombination rate, the attenuation factor β = 0.08 ??1 is estimated for the PCDTBT/PC71BM blend. Such a low attenuation factor is probably caused by a high degree of hole delocalization along the PCDTBT chain.
关键词： PCDTBT/PC71BM blend,electron spin echo,geminate recombination,organic solar cells,charge transfer state
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
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Effect of Annealing Treatment on Optical and Electrical Properties of PCDTBT:Graphene Hybrid Structure for Photovoltaic Application
摘要： Indium tin oxide (ITO)/poly[N-9￠-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2￠,1￠,3￠-benzothiadiazole)] (PCDTBT):graphene/Al structures have been elaborated. By applying a specific elaboration method, we succeeded in dispersing expandable graphene oxide in organic solvent (N,N-dimethylformamide, DMF) to obtain graphene oxide and insert it into a PCDTBT matrix. The effect of annealing treatment of PCDTBT:graphene films on the optical and electrical properties were studied. The obtained results showed a remarkable effect of the annealing treatment on the optoelectronic properties. The ultraviolet–visible (UV–Vis) spectra showed that the light harvesting was increased and the orderly stacking of the polymer chains was enhanced. The photoluminescence results showed a red-shift of about 10 nm in case of heat treatment at 150°C, related to an increase of the conjugation length of the polymer chains. The electrical parameters, such as the series resistance (Rs), ideality factor (n), and barrier height (/b), were calculated. We found that thermal annealing reduced both the series resistance Rs and barrier height value /b, significantly. These results indicate that annealing treatment improves the transport phenomenon in the active layer. In addition, the Log(J)–Log(V) curves suggested that the charge transport is governed by a space-charge-limited mechanism current. The effective carrier mobility (leff) was on the order of 10?5 cm2/V.
关键词： annealing treatment,hybrid structure,PCDTBT,graphene oxide,bulk heterojunction,Nanocomposite
更新于2025-09-11 14:15:04
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Optimizing nanoscale morphology and improving Carrier transport of PCDTBT-PCBM bulk heterojunction by cyclic carboxylate nucleating agents
摘要： In this work, four cyclic carboxylate commercial nucleating agents, bicyclo [2.2.1] heptane-2,3-dicarboxylic acid disodium salt (HPN-68L), sodium salt of hexahydrophthalic acid (HHPA-Na), sodium benzoate (Be-Na) and calcium salt of hexahydrophthalic acid (HPN-20E) were respectively added into poly[N-9’-heptadecanyl-2,7-carbazole-alt-5,5-(4’,7’-di-2-thienyl-2’,1’,3’ benzothiadi-azole)] (PCDTBT)-[6,6]-phenyl C61-butyric acid methyl ester (PCBM) blend. Atomic force microscopy (AFM) and UV-vis measurements indicate that the addition of carboxylic acid sodium salts can effectively optimize the morphology of active layer, decrease the phase domain size and increase the optical absorption intensity of PCDTBT-PCBM blends. The PCDTBT-PCBM-additive ternary devices were fabricated and found that adding carboxylic acid sodium salts can improve the hole mobility, balance the hole and electron mobility and finally increase the power conversion efficiency (PCE). Fixed the additive content as 5%, the modulation ability of the bicyclic dicarboxylic acid sodium salt HPN-68L is best, monocyclic dicarboxylic acid sodium salt HHPA-Na comes second, monocyclic carboxylic acid sodium salt Be-Na is worst. The addition of carboxylic acid calcium salt HPN-20E has no effects on the morphology and optical absorption intensity of the PCDTBT-PCBM blend, and the photoelectric properties of PCDTBT-PCBM-HPN-20E ternary device decreases in comparison with those of pristine PCDTBT-PCBM binary device. The modulation ability of cyclic carboxylate is related to its surface free energy and its location in the PCDTBT-PCBM blend. HPN-68L locates in the interfacial region between PCDTBT and PCBM, other cyclic carboxylates locates in the PCBM. Our finding suggests the addition of cyclic carboxylic acid sodium salts can be a facile approach to optimize the morphology and increase the electrical properties of organic materials for future development of organic photovoltaic devices.
关键词： PCDTBT-PCBM bulk heterojunction,carrier transport,organic photovoltaic devices,cyclic carboxylate nucleating agents,nanoscale morphology
更新于2025-09-09 09:28:46