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In2Se3 nanosheets for harmonic mode-locked fiber laser
摘要： Two-dimensional materials with a sheet structure have excellent optical, electrical and mechanical properties, and have attracted much attention in recent years, especially In2Se3 (the N-type semiconductor compound), which has a rapid development in the fields of materials science and optical communication. In this paper, the nonlinear saturation absorption characteristics of In2Se3 are studied. The In2Se3 nanosheet dispersion can be used in ultrafast photonics applications. The nonlinear absorption is measured by power correlation method, and the modulation depth and saturation intensity are 3.8 % and 246.6 MW/cm2, respectively. More importantly, In2Se3 is used as a saturable absorber (SA) in a passively mode-locked erbium-doped fiber laser. The proposed mode-locked fiber laser is demenstrated with a center wavelength of 1529.4 nm, a fundamental frequency of 5.9 MHz, a spectral width of 3.96 nm, a pulse width of 1.38 ps, and a signal-to-noise ratio of 55 dB. For the first time, harmonic mode-locking with a high-repetition rate of 431 MHz is achieved when the pump power is 360 mW corresponding to 73rd-order harmonic mode locking. It can be seen that In2Se3 is indeed a new excellent photonic material, which can be used in fiber optic communication, SAs photonics,, laser material processing and light modulators.
关键词： harmonic mode-locked,high repetition frequency,mode-locked,In2Se3 SA
更新于2025-09-23 15:21:01
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Solution-processable PEDOT:PSS:?±-In2Se3 with enhanced conductivity as a hole transport layer for high-performance polymer solar cells
摘要： Two-dimensional (2D) nanosheets have attracted enormous attention in photovoltaic devices owing to their outstanding photoelectric properties in recent years. Herein, 2D α-In2Se3 nanosheets with higher conductivity and suitable work function are synthesized by liquid phase exfoliation method. To ameliorate the low conductivity of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) (2.21×10-3 S cm-1), α-In2Se3 nanosheets are directly added into PEDOT:PSS to obtain PEDOT:PSS:α-In2Se3 composite film. The composite film exhibits excellent optical transmittance, suitable work function, and enhanced conductivity (1.54×10-2 S cm-1). To profoundly investigate the mechanism of conductivity improvement, XPS, Raman, EPR and AFM measurements are conducted. The results show that the synergistic effect of 2D α-In2Se3 nanosheets and isopropanol/deionized water cosolvent screens the Coulombic attraction among PEDOT and PSS. The screening effect results in the partial removal of PSS and the benzoid-quinoid transition of PEDOT. In addition, α-In2Se3 nanosheets may serve as physical linkers for PEDOT chains. Both effects are beneficial to increase interfacial contact area between PEDOT chains and form a larger conductive network of PEDOT, leading to an enhanced conductivity. The composite film is first employed as a hole transport layer (HTL) in polymer solar cells (PSCs). The power conversion efficiency (PCE) of PBDB-T:ITIC-based device with composite HTL is 10% higher than that of unmodified PBDB-T:ITIC-based device, and the maximum PCE of 15.89% is achieved in PM6:Y6 system. More interestingly, the stability of devices with composite HTL is improved owing to the partial removal of PSS. Thus the PEDOT:PSS:α-In2Se3 composite can be an application prospect HTL material in PSCs.
关键词： polymer solar cells,hole transport layer,α-In2Se3,PEDOT:PSS,stability
更新于2025-09-23 15:21:01
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Solution‐Processable Two‐Dimension α‐In <sub/>2</sub> Se <sub/>3</sub> as an Efficient Hole Transport Layer for High‐Performance and Stable Polymer Solar Cells
摘要： In this work, two-dimension (2D) α-In2Se3 nanosheet, a binary III-VI group compound semiconductor, is fabricated by liquid phase exfoliation method, and the photoelectric properties of α-In2Se3 material are investigated in depth. It is found that α-In2Se3 film exhibits significant conductivity, outstanding optical transmission and suitable work function. Combined with its smooth surface and preferable hydrophobicity, α-In2Se3 film can efficiently facilitate hole transporting in the polymer solar cells (PSCs). Owing to the aforesaid advantages, 2D α-In2Se3 nanosheet is employed as a hole transport layer (HTL) in conventional PSCs for the first time, and a relatively high power conversion efficiency (PCE) of 9.58% is achieved with the structure of ITO/α-In2Se3/PBDB-T:ITIC/Ca/Al, which is comparable to PEDOT:PSS-based devices (9.50%). Interestingly, it is demonstrated that α-In2Se3 film possesses excellent thermal stability in the range from room temperature to 280 °C and a PCE of 9.35% is achieved without annealing treatment of α-In2Se3 film, which exhibits a great potential of α-In2Se3 for annealing-free approach. Furthermore, the incorporation of α-In2Se3 HTL also remarkably enhances the long-term stability of PSCs compared with PEDOT:PSS-based devices. So the results show that 2D α-In2Se3 is a promising candidate to be an efficient and stable hole extraction layer.
关键词： solution processed,α-In2Se3,hole transport layer,polymer solar cells,thermal stability
更新于2025-09-12 10:27:22
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Photodetector based on heterostructure of two-dimensional WSe2/In2Se3
摘要： Heterojunctions formed by two-dimensional (2D) layered semiconducting materials have been studied extensively in the past several years. These van der Waals (vdW) structures have shown great potential in future electronic and optoelectronic devices. However, the optoelectronic performance of these devices is limited by the indirect band gap of the multilayer materials and low light absorption of single layer materials. Here, we fabricate photodetectors based on heterojunctions composed of n-type multilayer α-Indium Selenide (In2Se3) and p-type Tungsten Diselenide (WSe2) for the first time. The direct band gap of multilayer α-In2Se3 and type-II band alignment of the WSe2/In2Se3 heterojunction enable high optoelectronic performance of the devices at room temperature in the air. Without light illumination, the dark current is effectively suppressed to 10-13 A under -1 V bias and a high rectification ratio of 7.37×103 is observed. Upon laser illumination with the wavelength of 650 nm, the typical heterojunction device exhibits a photocurrent on/off ratio exceeding 1.24×105, a maximum photo responsivity of 26 mA/W and short photoresponse time of 2.22 ms. Moreover, the heterojunction photodetectors show obvious light response in the wavelength range from 650 nm to 900 nm. The present 2D vdW heterojunctions composed of direct band gap multilayer materials show great potential in future optoelectronic devices.
关键词： In2Se3,photodetector,two-dimensional materials,WSe2,direct band gap materials,heterojunction
更新于2025-09-11 14:15:04