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Investigation on voltage loss in organic triplet photovoltaic devices based on Ir complexes
摘要： Voltage losses in singlet material-based organic photovoltaic devices (OPVs) have been intensively studied, whereas, only a few investigations on triplet material-based OPVs (T-OPVs) are reported. To investigate the voltage loss in T-OPVs, two homoleptic iridium(III) complexes based on extended p-conjugated benzo[g]phthalazine ligands, Ir(Ftbpa)3 and Ir(FOtbpa)3, are synthesized as sole electron donors. T-OPVs are fabricated by mixing two donors with phenyl-C71-butyric acid methyl ester (PC71BM) as an electron acceptor. Insertion of oxygen-bridges as flexible inert d-spacers in Ir(FOtbpa)3 has slightly elevated both the lowest unoccupied molecular orbital and the highest occupied molecular orbital levels compared to those of Ir(Ftbpa)3, which results in a lower charge transfer (CT) state energy (ECT) for Ir(FOtbpa)3-based devices. However, a higher Voc (0.88 V) is observed for Ir(FOtbpa)3-based devices than those of Ir(Ftbpa)3 (0.80 V). To understand the above result, the morphologies of the two blend films are studied, which excludes the influence of morphology. Furthermore, radiative and non-radiative recombination in two devices is quantitatively investigated, which suggests that a higher Voc can be attributed to reduced radiative and non-radiative recombination loss for the Ir(FOtbpa)3-based devices.
关键词： charge transfer state energy,organic photovoltaic devices,triplet material-based OPVs,radiative and non-radiative recombination,iridium(III) complexes,voltage loss
更新于2025-09-12 10:27:22
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Dual Role of Graphene Quantum Dots in Active Layer of Inverted Bulk Heterojunction Organic Photovoltaic Devices
摘要： Graphene quantum dots (GQDs) have shown broad application prospects in the field of photovoltaic devices due to their unique quantum confinement and edge effects. Here, we prepared GQDs by a photon-Fenton reaction as reported in our previous work, which has great advantage in the preparation scale. The photoelectric properties of the inverted hybrid solar cells based on poly(3-hexylthiophene) (P3HT): (6,6)-phenyl-C61 butyric acid methylester (PCBM):GQDs and P3HT:GQDs with different contents of GQDs as the active layers are demonstrated, as well as their morphology and structure by atomic force microscopy images. Then, the different roles of GQDs played in the ternary (P3HT:PCBM:GQDs) and binary (P3HT:GQDs) hybrid solar cells are studied systematically. The results indicate that the GQDs provide an efficient excition separation interface and charge transport channel for the improvement of hybrid solar cells. The preliminary exploration and elaboration of the role of GQDs in hybrid solar cells will be beneficial to understand the interfacial procedure and improve device performance in the future.
关键词： photovoltaic devices,hybrid solar cells,PCBM,photon-Fenton reaction,P3HT,Graphene quantum dots
更新于2025-09-12 10:27:22
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Cation exchange synthesis of CuIn <sub/>x</sub> Ga <sub/>1?x</sub> Se <sub/>2</sub> nanowires and their implementation in photovoltaic devices
摘要： CuInxGa1(cid:1)xSe2 (CIGS) nanowires were synthesized for the ?rst time through an in situ cation exchange reaction by using CuInSe2 (CIS) nanowires as a template material and Ga-OLA complexes as the Ga source. These CIGS nanowires maintain nearly the same morphology as CIS nanowires, and the Ga/In ratio can be controlled through adjusting the concentration of Ga-OLA complexes. The characteristics of adjustable band gap and highly e?ective light-absorbances have been achieved for these CIGS nanowires. The light-absorbing layer in photovoltaic devices (PVs) can be assembled by employing CIGS nanowires as a solar-energy material for enhancing the photovoltaic response. The highest power conversion e?ciency of solar thin ?lm semiconductors is more than 20%, achieved by the Cu(InxGa1(cid:1)x)Se2 (CIGS) thin-?lm solar cells. Therefore, these CIGS nanowires have a great potential to be utilized as light absorber materials for high e?ciency single nanowire solar cells and to generate bulk heterojunction devices.
关键词： CIGS nanowires,solar cells,photovoltaic devices,light absorber materials,cation exchange
更新于2025-09-12 10:27:22
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Print flexible solar cells
摘要： Conventional silicon solar cells account for more than 90% of global production, yet making them uses energy equivalent to about 10% of their lifetime output. The future of solar energy depends on a union of new and old technologies. If photovoltaic (PV) devices that turn light into electricity could be mass produced with printing presses, as if they were newspapers or banknotes, they could be affordable and ubiquitous. Conventional, silicon-based, solar panels are rigid and bulky. Small, thin and flexible PV devices on films are already being made that are lightweight and translucent. These use little material and can generate electricity in low light, even indoors. Integrating them into phones and watches, as well as walls and windows, would transform the world’s energy generation, reduce pollution and mitigate climate change.
关键词： photovoltaic devices,solar cells,printing technology,flexible solar panels,renewable energy
更新于2025-09-11 14:15:04
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Spectral response measurements of each subcell in monolithic triple-junction GaAs photovoltaic devices
摘要： Multijunction photovoltaic devices have gained attention for both solar cells and wireless power transmission. Herein, we present the spectral response of each subcell in a monolithic triple-junction photovoltaic device composed of only GaAs subcells with different thicknesses, which clarifies current matching among the GaAs subcells under simulated solar illumination conditions. In addition, the spectral response curves of each subcell show that the power-dependent spectral responses under laser illumination with wavelengths of 405, 660, and 785 nm are explained by the top GaAs subcell, which has a slightly lower shunt resistance and experiences the effects of luminescent coupling.
关键词： luminescent coupling,photovoltaic devices,spectral response,multijunction,GaAs
更新于2025-09-11 14:15:04
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Highly Efficient Indoor Organic Solar Cells by Voltage Losses Minimization through Fine-tuning of Polymer Structures
摘要： Herein we report a detailed study on the optoelectronic properties, photovoltaic performance, structural conformation, morphology variation, charge carrier mobility and recombination dynamics in bulk heterojunction (BHJ) solar cells comprising of a series of donor-acceptor (D-A) conjugated polymers as electron donors based on benzodithiophene (BDT) and 5,8-bis(5-bromothiophen-2-yl)-6,7-difluoro-2,3-bis(3-(octyloxy)phenyl)quinoxaline as a function of the BDT’s thienyl substitution (alkyl (WF3), alkylthio (WF3S) and fluoro (WF3F)). It is manifested the synergistic positive effects of the fluorine substituents on the minimization of the bimolecular recombination losses, the reduction of the series resistances (RS), the increment of the shunt resistances (RSh), the suppression of the trap-assisted recombination losses, the balanced charge transport, the finer nanoscale morphology and the deeper highest occupied molecular orbital (EHOMO) versus the alkyl- and alkylthio- substituents. According to these findings, WF3F:[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) based-organic photovoltaic (OPV) device is a scarce example that feature a high power conversion efficiency (PCE) of 17.34% under 500 lx indoor LED light with a high open-circuit voltage (VOC) of 0.69 V, due to the suppression of the voltage losses and a PCE of 9.44% at 1-sun (100 mW/cm2) conditions, simultaneously.
关键词： Series and Shunt resistances,Coherence length,Conjugated polymers,Wide-angle X-ray scattering,Organic photovoltaic devices,Recombination losses,Indoor lighting conditions
更新于2025-09-11 14:15:04
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Systematic control of the rate of singlet fission within 6,13-diphenylpentacene aggregates with PbS quantum dot templates
摘要： Lead chalcogenide quantum dots (QDs) are promising acceptors for photovoltaic devices that harness the singlet fission (SF) mechanism. The rate of singlet fission of polyacenes in the presence of QDs is a critical parameter in determining the performance of such devices. The present study demonstrates that the rates of SF in a pentacene derivative, 6,13-dipenylpentacene (DPP), are modulated by forming coaggregates with PbS QDs in aqueous dispersions. PbS QDs generally accelerate SF within DPP aggregates, and the extent of acceleration depends on the size of the QD. The average rate of SF increases from 0.074 ps-1 for DPP-only aggregates to 0.37 ps-1 within DPP-D co-aggregates for QDs with radius 2.2 nm, whereas co-aggregation with the smallest (r = 1.6 nm) and largest (r = 2.7 nm) QDs we tried only slightly change the SF rate. The rate variation is associated with (i) the density of surface ligands, which is influenced by the faceting of the PbS surface, and (ii) the local dielectric constant for the DPP. To accelerate SF, the ligands should be dense enough to provide sufficient affinity for DPP aggregates and effectively perturb the perpendicular alignment of DPP monomers within aggregates to increase the intermolecular coupling that promotes SF, but should not be too dense so as to form a low dielectric environment that disfavors SF. The study suggests that it is critical to consider the influence of the microenvironment of QD surface on photophysical processes when fabricating QD/organic hybrid devices.
关键词： pentacene,photovoltaic devices,PbS,quantum dots,singlet fission
更新于2025-09-11 14:15:04
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Peculiar Photoinduced Electron Transfer in Porphyrin-Fullerene Akamptisomers
摘要： Porphyrin-fullerene dyads are promising candidates for organic photovoltaic devices. Electron transfer (ET) properties of the molecular devices depend significantly on the mutual position of the donor and acceptor. Recently, a new type of molecular isomerism (akamptisomerism) has been discovered. In the present study, we explore how photoinduced ET can be modulated by passing from one akamptisomer to another. To this aim, four akamptisomers of quinoxalinoporphyrin–[60]fullerene complex are selected for the computational study. The most striking finding is that, depending on the isomer, the porphyrin unit in the dyad can act as either electron donor or electron acceptor. Thus, the stereoisomeric diversity allows one to change the direction of ET between the porphyrin and fullerene moieties. To understand the effect of akamptisomerism on the photoinduced ET processes a detailed analysis of initial and final states involved in the ET is performed. The computed rate for charge separation is estimated to be in the region of 1-10 ns-1. The formation of a long-living quinoxalinoporphyrin anion-radical species is predicted.
关键词： quinoxalinoporphyrin–[60]fullerene complex,Porphyrin-fullerene dyads,photoinduced electron transfer,organic photovoltaic devices,akamptisomerism
更新于2025-09-10 09:29:36
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Disentangling the Electron and Hole Dynamics in Janus CdSe/PbSe Nanocrystals through Variable Pump Transient Absorption Spectroscopy
摘要： CdSe/PbSe Janus hetero-nanocrystals (HNCs) represent an interesting system where structurally immiscible CdSe and PbSe co-exist in a single structure with intermixed electronic states. Here, we have investigated the carrier dynamics in Janus CdSe/PbSe HNCs through ultrafast transient absorption spectroscopy by selectively exciting either the CdSe or the PbSe domains. Upon excitation of the CdSe domain sub-picosecond hole transfer to the hybrid interfacial PbSe states were identified. On the other hand, the transfer of hot electron from PbSe to CdSe was evident upon creation of hot electrons in PbSe domain without exciting the CdSe domain. The photo-excited hot hole also gets transferred to the hybrid interfacial states in sub-ps time (~1ps) bleaching the corresponding transition. The decay of the localized hole was found to be much slower compared to the electron which can be beneficial for carrier extraction and multiexciton generation. The finding of hot electron transfer in a single structure and slow decay of holes can thus prove to be advantageous for future design of photovoltaic devices.
关键词： carrier dynamics,ultrafast transient absorption spectroscopy,CdSe/PbSe Janus hetero-nanocrystals,photovoltaic devices,hot electron transfer
更新于2025-09-10 09:29:36
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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