Hole transport layers (HTLs) have a significant role in the performance of organic and organic-inorganic solar cells. In this experiment, we have investigated HTLs for Pb-Sn binary perovskite solar cells (PSCs) to maximize the power conversion efficiency (PCE). CuI, PTAA, and PEDOT:PSS were chosen as HTLs to fabricate the MAPb0.75Sn0.25(I0.50Br0.50)3 perovskite solar cells. The solar cells were fabricated using an inverted p-i-n structure where we used ITO/HTL/Perovskite/C60/BCP/Al materials stack. For PSCs containing CuI, PTAA and PEDOT:PSS as HTL, we obtained the PCE of 3.81%, 3.11 and 6.5%, respectively, with unchanged other experimental condition. Also, PEDOT:PSS HTL-based solar cells deliver higher short circuit current of 16.37 mA/cm2 compared to CuI and PTAA HTL based binary perovskite solar cells. For these binary PSCs, PEDOT:PSS is the best choice to maximize power conversion efficiency.
The availability of printable dielectric materials and their printability is one of the major roadblocks to printed flexible electronics. Here, we report the performance of fully printed field-effect transistors using polyvinyl alcohol (PVA) as dielectric and carbon nanotube (CNT) as a semiconducting layer. As fewer numbers of research are available on printed PVA films, here we investigate ink formulation and printing parameters for PVA and their effects on device performances. Aerosol jet Printer was used to obtain a highly dense CNT network and pinhole-free thin PVA dielectric layer that resulted in a high on/off ratio and drain current. This completely printed transistor with polymer dielectric will be a great contribution to flexible electronic devices.
Anti-solvent-free one-step deposition of perovskite thin film shows promising potential for application in slot-die or roll-to-roll mass-fabrication processes of perovskite solar cells. The continuous coverage was confirmed by PV response of devices made using the one-step deposition process. In this work, we have developed a process to deposit MAPb0.75Sn0.25(I0.5Br0.5)3 perovskite thin films without anti-solvent adding MAAc to the ink. By varying the Br content of the perovskite precursor, we were able to tune the bandgap. Fabricated solar cells with the structure ITO/CuI/ MAPb0.75Sn0.25(I0.5Br0.5)3 /C60/BCP/Al with PCE of 4.59% show the path of the fabrication process of antisolvent-free tin-lead-based solar cells
In recent years, PPDT2FBT is getting researchers’ attention due to its applications in solar cells and optoelectronic devices. Although the main applications of this material are based on the optical properties. However, the optical dispersion of this material has not been studied yet over the UV and visible spectral range. We report the optical properties of PPDT2FBT for the wavelength range of 300 nm to 900 nm using a variable angle spectroscopic ellipsometry (SE). The refractive index (n) and extinction coefficient (k) of spin coated PPDT2FBT thin films were determined at room temperature. Glass of known optical properties was used as the substrates for convenience. To build an optical model the surface morphology was studied using atomic force microscopy (AFM). Then an optical model was developed based on the extracted properties. The optical properties were found to be consistent with the UV-Vis data. The bandgap was estimated from the absorption properties. Finally, the developed ellipsometry model was used for thickness measurement of PPDT2FBT thin films. The measured data agreed well with the data collected using other direct thickness measurement techniques of the same thin film. This developed model can be useful for designing effective optoelectronic devices as well as measuring the thickness of thin films in a nondestructive way.
We have demonstrated the highest conical refraction (CR) laser output power to date by placing a CR crystal inside of a diode-pumped Nd:YVO laser cavity. The CR crystal did not have a significant influence on laser output power as well as efficiency. The CR laser produced the maximum output power of 3.68 W with the slope efficiency of 42 % and opticalto- optical efficiency of 34 %. Therefore, this approach could be an attractive pathway for further power scaling of the CR lasers.
A conical refraction (CR) laser based on a separate gain medium (Nd:YVO4) and an intracavity CR element (KGW) was demonstrated. The decoupling of the gain and CR media enabled the laser to produce a well-behaved CR laser beam with excellent quality, while reducing the complexity of the pumping scheme. The proposed laser setup has the potential for power scaling using the efficient diode pumping approach and the properties of the generated CR beam are independent from the laser gain medium.
A new heterostructure based on AlxIn1-xN/GaN high electron mobility transistor (HEMT) on SiC substrate has been
proposed for high frequency, where it offers the best performance in comparison to other two heterostructures like on
AlxGa1-xN/GaN and InxGa1-xN/GaN. We have investigated the effect of different higher output characteristics in
comparison to conventional AlxGa1-xN/GaN and InxGa1-xN/GaN with the AlxIn1-xN/GaN heterostructure, where the drain
current is maximum for AlxIn1-xN/GaN and AlxGa1-xN/GaN heterostructure HEMT respectively for the same barrier
thickness and for the same gate source voltage.
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