- 标题
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- 实验方案
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Effect of insertion of bathocuproine buffer layer at grating-structured cathodea??organic-layer interface in bulk-heterojunction solar cells
摘要： A grating-structured interface of a poly(3-hexylthiophene) (P3HT) and n-type [6,6]-phenyl-C61-butyric acid methyl ester (PCBM)-based bulk-heterojunction (BHJ) photovoltaic (PV) cell was designed and fabricated to obtain a desirable thickness distribution of the deposited bathocuproine (BCP) buffer layer to efficiently utilize its potentials. As a master mold of the grating-structure, a commercially available recordable digital versatile disc (DVD-R) substrate was employed. The grating-structured surface of the P3HT:PCBM layer was successfully produced by duplication from a poly(dimethylsiloxane) secondary mold using the spin cast molding technique. From morphological observations of the grating-structured surface covered with vapor-deposited BCP, we roughly estimated the ratio of the BCP thickness at “walls” to that at “top” and “bottom” regions to be ～0.5. The grating-type BHJ PV cell with a 5-nm-thick BCP layer exhibited the maximum power-conversion efficiency (ηp) of 3.51%. Compared with the conventional flat-type BHJ PV cell with a 20-nm-thick BCP layer, the performance of the grating-type BHJ PV cell with a 20-nm-thick BCP layer was remarkably improved, owing to the contribution of the wall side contact, which provides a lower-barrier path of the electrons toward the cathode through the thinner BCP layer.
关键词： bathocuproine buffer layer,grating-structured interface,bulk-heterojunction solar cells,power-conversion efficiency
更新于2025-09-23 15:19:57
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Quantification of Photophysical Processes in Alla??Polymer Bulk Heterojunction Solar Cells
摘要： Combined data of transient optical and electro-optical experiments reveals the efficiency-determining processes in all-polymer solar cells and allows precisely quantifying their yields. For the test system presented here, field-dependent charge separation is shown to limit the fill factor and thus the performance by comparing the experimentally-measured current-voltage characteristics to those reproduced by drift-diffusion simulations using the spectroscopically-determined kinetic parameters.
关键词： all-polymer solar cells,bulk heterojunction,non-fullerene acceptors,transient absorption,organic photovoltaics
更新于2025-09-23 15:19:57
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Higha??Accuracy Photoplethysmography Array Using Neara??Infrared Organic Photodiodes with Ultralow Dark Current
摘要： Reflectance oximeters based on organic photodiode (OPD) arrays offer the potential to map blood pulsation and oxygenation via photoplethysmography (PPG) over a large area and beyond the traditional sensing locations. Here, an organic reflectance PPG array based on 16 × 16 OPD pixels is developed. The individual pixels exhibit near-infrared sensitivity up to ≈950 nm and low dark current density in the order of 10?6 mA cm?2. This results in high-quality PPG signals. Analysis of the full PPG waveform yields insight on the artery stiffness and the quality of blood circulation, demonstrating the potential of these arrays beyond pulse oximetry and heart-rate calculation.
关键词： photoplethysmography,organic photodiodes,bulk heterojunction,heartbeat,pulse oximetry
更新于2025-09-23 15:19:57
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Realizing high detectivity organic photodetectors in visible wavelength by doping highly ordered polymer PCPDTBT
摘要： A new method for realizing the response broadening of organic photodetectors (OPDs) using highly ordered polymer PCPDTBT doping has been proposed in this paper. The effects of PCPDTBT doping on the optical and electrical properties of OPDs were investigated experimentally. It was found that when the mass ratio of PTB7:PCPDTBT:PC61BM was 8.5:1.5:15, the response spectrum of the OPDs was broadened to 380–830 nm. The responsivity (R) and external quantum efficiency (EQE) of the OPDs reached 396, 244, 189 mA/W and 78%, 57%, 51% under 630, 530 and 460 nm illumination and (cid:0) 1 V bias, respectively, and the detectivity (D*) reached 1011 Jones. The results showed that the addition of PCPDTBT to PTB7:PC61BM increased the absorption of light at 700–830 nm. At the same time, the addition of PCPDTBT promotes the exciton dissociation interface in the active layer from the original one to the current three, they are PTB7:PCPDTBT, PTB7:PC61BM and PCPDTBT:PC61BM, which increase the probability of exciton dissociation in the active layer. In addition, the addition of highly ordered polymer PCPDTBT promotes the crystallization of the film and optimizes the carrier transport of the film. These synergistic effects promote the photocurrent of the OPDs.
关键词： Ternary bulk heterojunction,Exciton dissociation,Organic photodetectors,Microscopic morphology
更新于2025-09-23 15:19:57
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Thienyl Sidechain Substitution and Backbone Fluorination of Benzodithiophene-Based Donor Polymers Concertedly Minimize Carrier Losses in ITIC-Based Organic Solar Cells
摘要： Non-fullerene acceptor (NFA) based organic solar cells have outperformed fullerene-based devices, yet their photophysics is less well understood. Herein, changes in the donor polymer backbone side-chain substitution and backbone fluorination in benzodithiophene (BDT)-thiophene copolymers are linked to the photophysical processes and performance of bulk heterojunction (BHJ) solar cells, using ITIC as NFA. Increased geminate recombination is observed when the donor polymer is alkoxy-substituted in conjunction with faster non-geminate recombination of free charges, limiting both the short circuit current and device fill factor. In contrast, thienyl-substitution reduces geminate recombination, albeit non-geminate recombination remains significant, leading to improved short circuit current density, yet not fill factor. Only the combination of thienyl-substitution and polymer backbone fluorination yields both efficient charge separation and significantly reduced non-geminate recombination, resulting in fill factors (FFs) in excess of 60 %. Time-delayed collection field measurements ascertain that charge generation is field-independent in the thienyl-substituted donor polymer:ITIC systems, while weakly field dependent in the alkoxy-substitued polymer:ITIC blend, indicating the low FFs are primarily caused by non-geminate recombination. This work provides insight into the interplay of donor polymer structure, BHJ photophysics, and device performance for a prototypical NFA, namely ITIC. More specifically, it links the donor polymer chemical structure to quantifiable changes of kinetic parameters and the yield of individual processes in ITIC-based BHJ blends.
关键词： non-fullerene acceptor,ultrafast spectroscopy,bulk heterojunction,charge generation,organic photovoltaics
更新于2025-09-23 15:19:57
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Impact of Polymer Backbone Fluorination on the Charge Generation/Recombination Patterns and Vertical Phase Segregation in Bulk Heterojunction Organic Solar Cells
摘要： Incorporating fluorine (–F) substituents along the main-chains of polymer donors and acceptors is an effective strategy toward efficient bulk-heterojunction (BHJ) solar cells. Specifically, F-substituted polymers often exhibit planar conformations, leading to favorable packing, and electronic coupling. However, the effects of fluorine substituents on the charge generation and recombination characteristics that determine the overall efficiency of BHJ active layers remain critically important issues to examine. In this report, two PBDT[2X]T polymer analogs –poly[4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b′]dithiophene-thiophene] [PBDT[2H]T] and its F-substituted counterpart poly[4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b′]dithiophene-3,4-difluoro-thiophene] [PBDT[2F]T]—are studied to systematically examine how –F substituents impact the blend morphology, charge generation, carrier recombination and extraction in BHJ solar cells. Considering the large efficiency differences between PBDT[2H]T- and PBDT[2F]T-based BHJ devices, significant emphasis is given to characterizing the out-of-plane morphology of the blend films as vertical phase-separation characteristics are known to have dramatic effects on charge transport and carrier extraction in polymer-fullerene BHJ solar cells. Herein, we use electron energy loss spectroscopy (EELS) in tandem with charge transport characterization to examine PBDT[2X]T-fullerene blend films. Our analyses show that PBDT[2H]T and PBDT[2F]T possess very different charge generation, recombination and extraction characteristics, resulting from distinct aggregation, and phase-distribution within the BHJ blend films.
关键词： vertical phase segregation,bulk heterojunction,polymer backbone fluorination,organic solar cells,charge generation and recombination
更新于2025-09-23 15:19:57
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Toward efficient polymer solar cells with thick bulk heterojunction by introducing iridium complex as an aggregation reshaping auxiliary
摘要： The morphology control of thick bulk heterojunction (BHJ) polymer solar cells (PSCs) is an important factor to determine their power conversion efficiency (PCE). Particularly, during the building of phase separation, aggregation morphology plays a prominent role in the control of both horizonal and vertical gradient distribution of donor/acceptor (D/A) in thick BHJ. In this work, we introduced a novel iridium complex of (tfmppy)2Ir(tpip) into the active layer of PffBT4T-2OD: PC71BM as an “aggregation reshaping auxiliary” to form a long and narrow aggregation shape in both horizontal and vertical directions. Through characterizing the morphology of active layer in details, it was found that the combination of 5% (tfmppy)2Ir(tpip) assists PffBT4T-2OD aggregation shape with a 1: 2.5 aspect ratio while maintaining high crystallinity. In addition, the results showed that the (tfmppy)2Ir(tpip) facilitates efficient exciton dissociation and charge transport because of increased contacting area of D/A interface. As a result, the short circuit current (JSC) and fill factor (FF) performances were both improved contemporaneously, leading to a 20.3% enhancement in PCE.
关键词： Charge transport,Polymer solar cells,Thick bulk heterojunction,Aggregation reshaping auxiliary,Iridium complex
更新于2025-09-23 15:19:57
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Numerical modelling of non-fullerene organic solar cell with high dielectric constant ITIC-OE acceptor
摘要： The low dielectric constant of organic semiconductors has been a limiting factor in the organic photovoltaics. Non-Fullerene Acceptor Bulk Heterojunction (NFA-BHJ) organic solar cells with high dielectric constant acceptors have been gaining a lot of attention. No simulation work has been done on NFA-BHJ organic solar cell with a high dielectric constant acceptor so far to study the influence of various material parameters on the device performance. In this work, a comprehensive device modelling of the conventional structure of NFA-BHJ with poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b]dithiophene)-co-(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl)benzo[1,2-c:4,5-c]dithiophene-4,8-dione)] (PBDB-T)as the polymer donor and (3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetraki(4-hexylphenyl)-dithieno [2,3-d:2,3-d]-s-indaceno [1,2-b:5,6-b]dithiophene)) with Oligo-Ethylene side chain (ITIC-OE) as the non-fullerene acceptor is performed. We did a detailed analysis on the impact of technological parameters on the cell performance and optimized the device characteristics to produce improved efficiency. Numerical simulation is done using SCAPS 1-D program and the validity of simulated output has been verified by comparing with the measurements from reported literature. Optimization of the device parameters produced an improved device performance with an open circuit voltage of 0.9562 V, short circuit current density of mA/cm2, Fill factor of 69.75 % and a power conversion efficiency of 11%. The results are encouraging to develop NFA-BHJ organic solar cells with high dielectric constant acceptors in the near future.
关键词： numerical modelling,Non-Fullerene Acceptor Bulk Heterojunction,high dielectric constant,ITIC-OE acceptor,organic solar cells
更新于2025-09-23 15:19:57
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Investigation of Non-ideality Factors for a P3HT: PCBM Based Bulk Heterojunction Organic Solar Cell in Presence of Silver Nanoparticles
摘要： Solar cells are a potential option to meet the growing energy requirements of humans. Organic solar cells (OSCs) represent a class of solar cells that is a part of the third generation solar cell technology. The quest for obtaining enhanced OSC efficiencies has led to the incorporation of metallic nanoparticles (NPs) in the OSCs. Metallic NPs increase the incident light absorption instances, thus increasing the obtainable cell efficiencies. Different parameters and factors need to be considered for obtaining the optimum NP specifications. Investigations of the mechanism of light absorption after the introduction of NPs in the OSC are critical. Hence theoretical simulations for such OSCs are important. An overview of the different solar cell characterization techniques is presented in this paper. Simulations are carried out for these characterization techniques to study the behavior of the P3HT:PCBM based OSC in which silver NPs are incorporated in the active layer. The simulations are carried out for the cell structure in the presence of different non-ideality factors. The non-idealities include mobility limitations, presence of traps, recombination losses, low generation, presence of non-ideal values of series and shunt resistances, the effect of doping, etc. The simulated characterization techniques can be utilized for the performance study and parameter extraction of these NP incorporated OSCs.
关键词： Absorption,Metallic nanoparticles,Active layer,Bulk heterojunction,Cell characterization,Organic solar cell
更新于2025-09-23 15:19:57
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Determining the sequence and backbone structure of a??semi-statisticala?? copolymers as donora??acceptor polymers in organic solar cells
摘要： Organic photovoltaics (OPVs) are attracting significant attention due to the growing demand for economically viable and renewable energy sources. With efficiencies exceeding 16.5%, single junction bulk heterojunction (BHJ) devices are amongst the most promising and are nearing commercialisation. One recent avenue of research has focused on statistical conjugated copolymers. However, a detailed investigation as to why these materials can achieve higher power conversion efficiencies than their regular alternating counterparts is seldom reported. This work describes an investigation into donor–acceptor polymers demonstrating how differing monomer activities can lead to differing microstructures in a simple batch reaction, which in turn demonstrates promising optoelectronic and morphological properties required for organic photovoltaic devices. A one pot condensation polymerisation reaction with three monomers leads to an ABA triblock structure from differing monomer reactivities. This structure in turn leads to visualised phase separation which is possibly linked to an increase in performance. Further to this we report on the reliability of the Stille coupling for the synthesis of conjugated polymers.
关键词： Organic photovoltaics,Donor–acceptor polymers,Bulk heterojunction devices,Statistical conjugated copolymers,Stille coupling
更新于2025-09-23 15:19:57