- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Numerical analysis of metal-semiconductor junctions ITO/p-a-Si:H and n-c-Si/Al on silicon heterojunction solar cells
摘要： Thin layers (HIT) solar cell with the structure: Indium Tin Oxide (ITO)/hydrogenated p-doped amorphous silicon (p-a-Si:H)/hydrogenated intrinsic polymorphous silicon (i-pm-Si:H)/n-doped crystalline silicon (n-c-Si)/Aluminium (Al). In this article we have studied the metal-semiconductor junctions at the front and back contacts (ITO/p-a-Si: H and n-c-Si/Al) on amorphous n-HIT solar cells. It is shown that an increase of the contact barrier height ?b0 at the front interface ITO/p-a-Si:H leads to an increase of the efficiency of amorphous n-HIT solar cells, while the performances of the studied solar cells fall when the contact barrier height ?bL at the back interface n-c-Si/Al is increased. Indeed, we thus improve the efficiency of the studied cell by choosing a TCO with high work function. Zinc oxide (ZnO) with a working function of 5.2 eV could be the best TCO for this type of solar cells. At the rear of the device, Aluminum is a good candidate for the elaboration of the back contact, because it has a work function equal to 4.06 eV considered one of the smallest compared to other metals.
关键词： potential barriers,Solar cells,simulation,heterojunction,silicon,ASDMP,Efficiency.
更新于2025-09-23 15:19:57
-
High quality silicon: Colloidal quantum dot heterojunction based infrared photodetector
摘要： The integration of silicon (Si) and nanomaterials with infrared light harvesting capability is a promising approach to fabricate large area infrared light detecting arrays. However, the construction of a high quality junction between Si and small bandgap colloidal quantum dots (CQDs) remains a challenge, which limited their photodetecting performance in the short wavelength infrared region (1.4 lm–3 lm). Herein, a layer of solution processed ZnO nanoparticles was inserted between silicon and CQDs to passivate the surface dangling bond of silicon. This signi?cantly reduces the carrier recombination between Si and CQDs. Meanwhile, the formation of the Si:CQD heterojunction structure enables effective carrier extraction. As a result, the photodetector shows the detecting range to the short wavelength infrared region (0.8 eV) and achieves a standard detectivity of 4.08 (cid:2) 1011 Jones at a bias of (cid:3)0.25 V at room temperature.
关键词： colloidal quantum dot,heterojunction,infrared photodetector,silicon
更新于2025-09-23 15:19:57
-
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
-
Graphene/GaAs heterojunction for highly sensitive, self-powered Visible/NIR photodetectors
摘要： Graphene/GaAs heterojunction has been demonstrated by transferring monolayer graphene on the surface of n-GaAs substrate, and the carrier transfer at the interface has been investigated by monitoring Raman shift of graphene on different substrates. The photovoltaic behavior and rectifying characteristic of the graphene/GaAs heterojunctions enable us to fabricate high-performance self-powered photodetector at zero bias. The device has been demonstrated to be sensitive to visible/near-infrared light (405–850 nm) at room temperature, giving rise to maximum responsivity of 122 mA W?1 and detectivity of 4.3 × 1012 Jones with quick response and recover time (0.5 ms and 0.35 ms), respectively. Such high photoelectric response is attributed to the efficient photo-generated carrier separation and transfer at the interface, which is caused by the strong built-in electric field between grapheme and GaAs because of a large barrier (0.87 eV). Our results confirm that the graphene/GaAs heterojunction has a great potential for high performance self-powered broadband photodetectors.
关键词： Photodetectors,Raman shift,Heterojunction,Graphene,Charge transfer
更新于2025-09-23 15:19:57
-
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
-
Lateral transport in silicon solar cells
摘要： We investigate lateral charge carrier transport in crystalline silicon solar cells. Under typical operation illumination of high-efficiency solar cells, a significant population of electrons and holes exist in the silicon wafer, leading to a non-negligible sheet conductance for both carrier types. To investigate the contribution of these sheet conductances to lateral transport in solar cells, we develop a model that calculates the effective series resistance of two sheet resistances coupled via a contact resistance. In solar cells, the upper sheet resistance describes the highly conductive region like a diffusion or a transparent conductive oxide, whereas the lower sheet resistance describes the silicon absorber. We find that the coupling contact resistance needs to be low to benefit from the lateral current flow in the silicon absorber. We show experimentally for silicon heterojunction solar cells that the silicon absorber supports lateral minority charge carrier transport for well-passivated devices. Another finding is that there is no principle advantage for coupling of the two sheet resistances for rear-junction or front-junction solar cells, as the pn-junction (for front-junction solar cells) does not prevent coupling. We suggest that for n-type silicon heterojunction solar cells, the observed advantage of the rear-junction over the front-junction architecture is due to practically lower contact resistance and higher mobility of electrons vs holes. We also confirm experimentally the importance of a low contact resistivity between the highly conductive region and the silicon absorber for effective coupling and present an innovative technique to extract contact resistance from comparing Suns-VOC and current–voltage measurements.
关键词： sheet conductance,silicon heterojunction,lateral transport,contact resistance,silicon solar cells
更新于2025-09-23 15:19:57
-
Temperature modulating rectifier behavior and photovoltaic response of VO<sub>x</sub> /Nb:SrTiO<sub>3</sub> heterojunctions
摘要： Vanadium oxide (VOx) is a promising candidate to be used for smart window and thermochromic photovoltaic modulating devices. The crystalline structure and electrical characteristics of VOx thin film deposited on NSTO were investigated. It was found that asymmetric hysteresis current between increasing and decreasing voltages occurs at 80, 300 and 360K. The photovoltaic effect was observed under irradiation by a pulse laser.
关键词： semiconductor-metal phase transition,photovoltaic modulating devices,heterojunction,thermochromism,resistance switch phenomena
更新于2025-09-23 15:19:57
-
First-principles study on photovoltaic properties of 2D Cs <sub/>2</sub> PbI <sub/>4</sub> -black phosphorus heterojunctions
摘要： Both 2D perovskite Cs2PbI4 and phosphorus are significant optoelectronic semiconductor materials, the optical-electrical characters between both contact interfaces are interesting topics. In present work, we demonstrate comparative investigation of optoelectronic properties for two kinds of electrical contact interfaces. i.e. Pb–I and Cs–I interfaces with black phosphorus contacts. The carrier transport, charge transferring and optical properties for both cases are investigated by using first principle calculation. Both contact interfaces exhibit type II band alignment with direct band gap. Charge carrier migration from Cs–I interface to black phosphorus is more strong than that of Pb–I interface by considering differential charge density and bader charge between distinct electrical contact interfaces. Besides, electron–hole effective masses of heterojunctions for both cases along different direction are investigated. Optical absorption coefficients of both cases are compared with those of free-standing Cs2PbI4 and black phosphorus in the visible spectrum. We systematically compared advantages and disadvantages of two kinds of contact interfaces for photovoltaic application, and the results reveal interfacial engineering of 2D heterojunction plays a important role in tuning optoelectronic properties.
关键词： optical property,first-principles,electronic structures,2D heterojunction,carrier effective masses,charge transfer
更新于2025-09-23 15:19:57
-
The role of CdS doping in improving SWIR photovoltaic and photoconductive responses in solution grown CdS/PbS heterojunctions
摘要： Low cost Short Wavelength Infrared (SWIR) photovoltaic (PV) detectors and solar cells are of very great interest, yet the main production technology today is based on costly epitaxial growth of InGaAs layers. In this study, layers of p-type, quantum confined (QC) PbS nano-domains (NDs) structure that were engineered to absorb SWIR light at 1550nm (Eg=0.8 eV) were fabricated from solution using the Chemical Bath Deposition (CBD) technique. The layers were grown on top of two different n-type CdS intermediate layers (Eg=2.4 eV) using two different CBD protocols on Fluoride Tin Oxide (FTO) substrates. Two types of CdS/PbS heterojunction were obtained to serve as SWIR PV detectors. The two resulting devices showed similar photoluminescence behavior, but a profoundly different electrical response to SWIR illumination. One type of CdS/PbS heterojunction exhibited a PV response to SWIR light, while the other demonstrated a photo-response to SWIR light only under an applied bias. To clarify this intriguing phenomenon, and since the only difference between the two heterojunctions could be the doping level of the CdS layer, we measured the doping level of this layer by means of the surface photo voltage (SPV). This yielded different polarizations for the two devices, indicating different doping levels of the CdS for the two different fabrication protocols, which was also confirmed by Hall Effect measurements. We performed current voltage measurements under super bandgap illumination, with respect to CdS, and got an electrical response indicating a barrier free for holes transfer from the CdS to the PbS. The results indicate that the different response does, indeed, originate from variations in the band structures at the interface of the CdS/PbS heterojunction due to the different doping levels of the CdS. We found that, unlike solar cells or visible light detectors having similar structure, in SWIR photodetectors, a type I heterojunction is formed having a barrier at the interface that limits the injection of the photo-exited electrons from the QC-PbS to the CdS side. Higher n-doped CdS generates a narrow depletion region on the CdS side, with a spike like barrier that is narrow enough to enable tunneling current, leading to a PV current. Our results show that an external quantum efficiency (EQE) of ~2% and an internal quantum efficiency (IQE) of ~20% can be obtained, at zero bias, for CBD grown SWIR sensitive CdS/PbS-NDs heterojunctions.
关键词： CBD,CdS/PbS heterojunction,SWIR photodetector,PbS NDs
更新于2025-09-23 15:19:57
-
Doped hydrogenated nanocrystalline silicon oxide layers for higha??efficiency ca??Si heterojunction solar cells
摘要： Hydrogenated nanocrystalline silicon oxide (nc-SiOx:H) layers exhibit promising optoelectrical properties for carrier-selective-contacts in silicon heterojunction (SHJ) solar cells. However, achieving high conductivity while preserving crystalline silicon (c-Si) passivation quality is technologically challenging for growing thin layers (less than 20 nm) on the intrinsic hydrogenated amorphous silicon ((i)a-Si:H) layer. Here, we present an evaluation of different strategies to improve optoelectrical parameters of SHJ contact stacks founded on highly transparent nc-SiOx:H layers. Using plasma-enhanced chemical vapor deposition, we firstly investigate the evolution of optoelectrical parameters by varying the main deposition conditions to achieve layers with refractive index below 2.2 and dark conductivity above 1.00 S/cm. Afterwards, we assess the electrical properties with the application of different surface treatments before and after doped layer deposition. Noticeably, we drastically improve the dark conductivity from 0.79 to 2.03 S/cm and 0.02 to 0.07 S/cm for n- and p-contact, respectively. We observe that interface treatments after (i)a-Si:H deposition not only induce prompt nucleation of nanocrystals but also improve c-Si passivation quality. Accordingly, we demonstrate fill factor improvement of 13.5%abs from 65.6% to 79.1% in front/back-contacted solar cells. We achieve conversion efficiency of 21.8% and 22.0% for front and rear junction configurations, respectively. The optical effectiveness of contact stacks based on nc-SiOx:H is demonstrated by averagely 1.5-mA/cm2 higher short-circuit current density thus nearly 1%abs higher cell efficiency as compared with the (n)a-Si:H.
关键词： silicon heterojunction (SHJ),carrier-selective-contacts (CSCs),interface treatments,optoelectrical properties,hydrogenated nanocrystalline silicon oxide (nc-SiOx:H)
更新于2025-09-23 15:19:57