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Hard mask processing of 20% efficiency back-contacted silicon solar cells with dopant-free heterojunctions
摘要： Single junction crystalline silicon (c-Si) solar cells featuring a conventionally doped interdigitated back contact heterojunction (IBC-SHJ) structure has approached a record efficiency of 26.6%, which is very close to the practical limit. However, integrating the interdigital p- and n-type amorphous silicon (a-Si:H) layers on the rear surface of Si substrate is of such complexity, posing problem of heavy dependences on expensive manufacturing techniques including plasma-enhanced chemical vapor deposition and photolithography. Its commercial potential is thus always being questioned, and to seek an alternative fabrication procedure, which adapts to cost-effective deposition parallel with simple patterning characteristics, has been a primary research target of related subjects. Here, we demonstrated 20.1% efficiency dopant-free IBC-SHJ solar cells by combining evaporated carrier-selective materials (MoOx and LiFx) and two-steps hard masks alignments, delivering substantial simplifications in the architecture and fabrication procedures. We investigated the effect of intrinsic a-Si:H films with different thicknesses on the passivation and contact resistance for both a-Si:H/MoOx and a-Si:H/LiFx contacts, showing 4 nm a-Si:H is better for high efficiency IBC-SHJ solar cells. We also found that the position of the metal target (electrode definition step) and isolation in between the busbar and the Si substrate are highly relevant to leakage and recombination and have great impact on the device performance. The dopant-free IBC-SHJ solar cells demonstrated here manifest enough confidence in our hard mask based fabrication procedure, with great potential for high performance-to-cost ratio in future.
关键词： solar cells,dopant-free,interdigitated back contact,silicon,carrier-selective,contacts,heterojunction
更新于2025-09-12 10:27:22
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Self-Powered Broad-band Photodetectors Based on Vertically Stacked WSe <sub/>2</sub> /Bi <sub/>2</sub> Te <sub/>3</sub><i>p–n</i> Heterojunctions
摘要： Semiconducting p-n heterojunctions, serving as the basic unit of modern electronic devices, such as photodetectors, solar-energy conversion devices, and light-emitting diodes (LEDs), have been extensively investigated in recent years. In this work, high performance self-powered broadband photodetectors were fabricated based on vertically stacked p-n heterojunctions though combining p-type WSe2 with n-type Bi2Te3 via van der Waals (vdW) epitaxial growth. Devices based on the p-n heterojunction show obvious current rectification behaviors in the dark and superior photovoltaic characteristics under light irradiation. Maximum short circuit current of 18 nA and open circuit voltage of 0.25 V can be achieved with the illumination light of 633 nm (power density: 26.4 mW/cm2), which are among the highest values compared with the ever reported 2D vdW heterojunctions synthesized by CVD method. Benefiting from the broadband absorption of the heterostructures, the detection range can be expanded from visible to near-infrared (375-1550 nm). Moreover, ascribing to the efficient carriers separation process at the junction interfaces, the devices can be further employed as self-powered photodetectors, where fast response time (≈210 μs) and high responsivity (20.5 A/W at 633 nm and 27 mA/W at 1550 nm) are obtained under zero bias voltage. The WSe2/Bi2Te3 p-n heterojunction-based self-powered photodetectors with high photoresponsivity, fast photoresponse time and broad spectral response will find potential applications in high speed and self-sufficient broadband devices.
关键词： p-n heterojunction,photodetector,photovoltaic,charge transfer,broadband,self-powered
更新于2025-09-12 10:27:22
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Influence of single-walled carbon nanotubes induced exciton dissociation improvement on hybrid organic photovoltaic devices
摘要： Torch-plasma-grown single-walled carbon nanotubes (SWCNTs) are integrated with regioregular poly(3-hexylthiophene) (P3HT) and a fullerene derivative 1-(3-methoxycarbonyl) propyl-1-phenyl[6,6]C61 (PCBM) as a hybrid photoactive layer for bulk heterojunction solar cell devices. We demonstrate that molecular information could be accurately obtained by time-of-flight secondary ion mass spectrometry through the hybrid organic photoactive solar cell layers when sputtering is performed using a Cs+ 2000 eV ion source. Furthermore, the photovoltaic (PV) performance of the fabricated devices show an increase in the short-circuit current density (Jsc) and the fill factor (FF) as compared to the pristine devices fabricated without SWCNTs. The best results are obtained with 0.5 wt. % SWCNT loads, where an open-circuit voltage (VOC) of 660 mV is achieved, with a Jsc of 9.95 mA cm?2 and a FF of 54%, leading to a power conversion efficiency of 3.54% (measured at standard test conditions, AM1.5 g). At this optimum SWCNT concentration of 0.5 wt. %, and to further understand the charge-transfer mechanisms taking place at the interfaces of P3HT:PCBM:SWCNT, Jsc is measured with respect to the light intensity and shows a linear dependency (in the double logarithmic scale), which implies that losses in the charge carrier are rather governed by monomolecular recombination. Finally, our results show that our hybrid devices benefit from the fullerene electron accepting nature and from the SWCNT fast electron transportation feature that improve substantially the exciton dissociation efficiency. The influence of the SWCNTs on the Fermi level and the work function of the photoactive composite and its impact on the PV performance is also investigated.
关键词： single-walled carbon nanotubes,bulk heterojunction,PCBM,hybrid organic photovoltaic devices,photovoltaic performance,P3HT,exciton dissociation
更新于2025-09-12 10:27:22
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Phase-transition modulated, high-performance dual-mode photodetectors based on WSe <sub/>2</sub> /VO <sub/>2</sub> heterojunctions
摘要： Photodetectors based on two-dimensional (2D) transition metal dichalcogenides (TMDs) can only be operated in a single photovoltaic or photoconductive mode, showing either high detectivity or high responsivity, but not both. An effort to develop a photodetector that can dynamically switch its working mode is indispensable for practical applications. In this article, we demonstrate a high performance, phase-transition modulated, dual-mode photodetector based on WSe2/VO2 heterojunction. Enabled by the insulator-to-metal transition of VO2, the WSe2/VO2 heterojunction can be regulated from a type-II heterojunction to a Schottky junction, showing a tunable built-in electric field at the heterojunction interface. This resulted in the dynamic switch of carrier transport and photoresponse in the heterojunction. With this dual-mode function, the new photodetector can have both a high detectivity and a large responsivity, surpassing the current performance of single mode 2D TMDs photodetectors. With a direct laser writing and erasing technique, the photoresponse of a WSe2/VO2 device can be locally modulated as desired. This dual mode detection of the WSe2/VO2 photodetector deepens the fundamental understanding of charge transfer in heterojunctions and favors versatile applications in photodetection.
关键词： Photodetectors,Phase-transition,2D materials,WSe2/VO2 heterojunction,Dual-mode
更新于2025-09-12 10:27:22
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Side chain effect on conjugated polymer/fullerene interfaces in organic solar cells: a DFT study
摘要： Considerable experimental research has been conducted on the influence of polymer alkyl side chains on the performance of bulk heterojunction organic solar cells. However, greater insight into the role of alkyl side chains in the polymer/fullerene interfacial regions is still needed. Using the dispersion-corrected density functional theory, we investigate the effect of alkyl side chains on the binding energies and electronic structures of various molecular pairings of fullerenes and monomers of organic copolymers (e.g. a pair of PC71BM and a monomer of copolymer PTB7 based on the thieno[3,4-b]thiophene/benzodithiophene repeat unit, PCBM and a copolymer PCDTBT based on 2,7-carbazole/dithienyl-2,1,3-benzothiazole and PC71BM and a copolymer PffBT4T-2OD based on difluorobenzothiadiazole/quaterthiophene). We find that the trends of the magnitudes of the binding energies vary with the lengths, types (branched or linear), and branching positions of alkyl side chains. Whenever possible, these results are compared with the efficiency trends of the corresponding organic solar cells. With the help of this comparison optimal side chain arrangements in bulk heterogeneous organic solar cells are identified. It is expected that these insights will aid in the production of more efficient organic photovoltaics.
关键词： binding energies,polymer alkyl side chains,organic solar cells,dispersion-corrected density functional theory,bulk heterojunction,electronic structures
更新于2025-09-12 10:27:22
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Reducing Photovoltage Loss in Inverted Perovskite Solar Cells by Quantum Dots Alloying Modification at Cathode Contact
摘要： The tremendous passion for inverted planar heterojunction perovskite solar cells (PSCs) is originated from their great tendency in the Roll-to-Roll process compatible fabrication and huge potential for integration into tandem solar cells. But the device efficiency is still lower than regular structured PSCs. Engineering of the cathode interface to efficiently control and reduce VOC loss light a lamp for increasing electrochemical properties and boosting overall performance. In this work, a simple interfacial modification strategy was developed by introducing a hybrid ligands interfacial layer to reduce VOC loss in PSCs with inverted planar structure. Heavily washed QDs was used as a neutral charged intermedia to enable alloying reaction to transfer ligands without damage perovskite. A band bending immediately generated on top surface of perovskite film after QDs modification, which was directly convinced by UPS and KPFM. This contributed to ~50 mV reduced VOC loss, leading to a VOC of 1.15 V and a PCE of 20.6% in inverted PSCs. Meanwhile, enhanced stability achieved for these devices after QDs modification, in which PCE keeping > 90% of initial value after 1000 hours' storage.
关键词： inverted planar heterojunction perovskite solar cells,perovskite quantum dots,photovoltage,electron transport layer,passivation
更新于2025-09-12 10:27:22
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Three-dimensional a-Si/a-Ge radial heterojunction near-infrared photovoltaic detector
摘要： In this work, three-dimensional (3D) radial heterojunction photodetectors (PD) were constructed over vertical crystalline Si nanowires (SiNWs), with stacked hydrogenated amorphous germanium (a-Ge:H)/a-Si:H thin film layer as absorbers. The hetero absorber layer is designed to benefit from the type-II band alignment at the a-Ge/a-Si hetero-interface, which could help to enable an automated photo-carrier separation without exterior power supply. By inserting a carefully controlled a-Si passivation layer between the a-Ge:H layer and the p-type SiNWs, we demonstrate first a convenient fabrication of a new hetero a-Ge/a-Si structure operating as self-powered photodetectors (PD) in the near-infrared (NIR) range up to 900 nm, indicating a potential to serve as low cost, flexible and high performance radial junction sensing units for NIR imaging and PD applications.
关键词： near-infrared,radial heterojunction,three-dimensional,a-Si/a-Ge,photovoltaic detector
更新于2025-09-12 10:27:22
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All-solution-processed UV-IR broadband trilayer photodetectors with CsPbBr3 colloidal nanocrystals as carriers-extracting layer
摘要： Colloidal quantum dots (CQDs) are very promising nanomaterials for optoelectronics due to their tunable bandgap and quantum confinement effect. Especially, all-inorganic CsPbX3 (X=Br, Cl and I) perovskite nanocrystals (NCs) have attracted enormous interests owing to their promising and exciting applications in photovoltaic devices. In this paper, all-solution-processed broadband photodetectors ITO/ZnO/CsPbBr3/PbS/Au with high-performance were presented. The role of CsPbBr3 QDs layer as the carriers-extracting layer in the trilayer devices was discussed. As compared with bilayer device ITO/ZnO/PbS/Au, both the dark currents and photocurrents under illumination from UV-IR broadband trilayer photodetector ITO/ZnO(80nm)/PbS(150nm)/CsPbBr3(50nm)/Au are enhanced, but the trilayer photodetector ITO/ZnO(80nm)/CsPbBr3(50nm)/PbS(150nm)/Au showed a maximum specific detectivity (D*) of 1.73×1012 Jones with a responsivity (R) of 5.31 A/W under 6.8 mW/cm2 405 nm illumination. However, another trilayer photodetector ITO/ZnO(80nm)/PbS(150nm)/CsPbBr3(50nm)/Au showed a maximum D* of 8.3×1012 Jones with a R of 35 A/W under 1.6 mW/cm2 980 nm illumination. Further, the underlying mechanism for the enhanced performance of trilayer photodetectors was discussed. Thus, this strategy of all-solution-processed heterojunction configuration paves a facile way for broadband photodetectors with high-performance.
关键词： broadband photodetectors,all-solution-processed heterojunction,Colloidal quantum dots (CQDs),CsPbBr3 perovskite nanocrystals,carrier-extraction layer
更新于2025-09-12 10:27:22
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Fabrication of a novel type visible-light-driven heterojunction photocatalyst: metal-porphyrinic metal organic framework coupled with PW12/TiO2
摘要： Metalloporphyrinic metal-organic framework (PCN-222) is a promising photocatalytic material due to its large surface area and 1D channel, exceptional stability, high visible-light capture capability, and semiconductor properties. Herein, we constructed a highly efficient visible-light-driven type II heterojunction photocatalyst PCN-222-PW12/TiO2 by one step solvothermal method. The 5 wt. % PCN-222-PW12/TiO2 showed the superior photocatalytic properties for degrading rhodamine B (RhB) and Ofloxacin, which are 10.69 and 10.48 times higher than pure TiO2 under same conditions. The excellent photocatalytic performance of PCN-222-PW12/TiO2 ternary composite material was attributed to the improved adsorption capacity of organic pollutants, optical absorption in the entire visible light region, and highly-efficient separation of photoinduced carriers. Besides, we found that h+, ?O2-, and ?OH are the main active elements in the photocatalytic degradation process. This will back up the higher photocatalytic activity of PCN-222-PW12/TiO2 compared with pure TiO2. The photocatalytic efficiency of composite maintained a similar level of photoactivity after four times recovery, which showed excellent stability and recyclability of PCN-222-PW12/TiO2. This work provides new insights into the fabrication porphyrin-MOF composite materials with high photocatalytic efficiency for environmental remediation.
关键词： Metalloporphyrin-MOF,PW12/TiO2,Photocatalysis,visible-light driven,type II heterojunction
更新于2025-09-12 10:27:22
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UV-blue photodetectors based on n-SnOx/p-diamond
摘要： High-performance self-powered UV-blue photodetector was fabricated based on n-SnOx/p-diamond heterojunction. The SnOx film was deposited on the high temperature and high pressure synthetic boron doped diamond wafer by RF magnetron sputtering. This heterojunction device exhibits a good rectification behavior with a rectification ratio of 3.15×104 at ± 3 V. At zero bias, the device responds in the wavelength ranging from 250nm to 500nm with a peak response at 350nm. The photoresponse rise time and decay time of the device are both less than 2 s under UV-blue illumination with different wavelengths. These results demonstrate that the n-SnOx/p-diamond heterojunction device has potential applications in the field of UV-blue detection.
关键词： Photodetector,RF sputtering,Self-powered,Thin films,Heterojunction,XPS
更新于2025-09-12 10:27:22