RESUMEN
Among the solution-processed devices, perovskite solar cells (PSCs) exhibit the highest power conversion efficiency (PCE) of over 25%; tremendous efforts are being undertaken to improve their stability. Recently, all-inorganic CsPbI2Br-based PSCs were reported to exhibit a significantly improved device stability, with a promising PCE of up to 16.79%. In this study, we report stable all-inorganic PSCs by incorporating novel dopant-free hole-transporting materials (HTMs). The synthesis strategy of the newly synthesized polymeric HTMs was similar to that of 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD), with the exception that they were designed to exhibit dopant-free characteristics. In particular, their polymeric backbone structure was significantly simpler than that of spiro-OMeTADs, and they were easily synthesized in two steps from commercially available chemicals, with an overall yield of â¼50%. The cost of synthesis at the laboratory scale was calculated to be at least 2.4 times cheaper than that of spiro-OMeTADs. The PCE of dopant-free HTM-based PSCs was 11.01%, which is 1.5 times higher than that of the dopant-free spiro-OMeTAD-based devices (7.52%) and comparable to that of the doped spiro-OMeTAD-based devices (12.22%). Notably, the stability of the device based on our dopant-free HTM to atmospheric oxygen and moisture as well as heat and light irradiation was superior to that of devices based on doped and dopant-free spiro-OMeTAD HTMs. On consideration of the synthesis cost, device efficiency, and device stability, our dopant-free HTM is highly promising for all-inorganic PSCs.
RESUMEN
We have proposed, prepared, and characterized Pt-inserted Ga-doped ZnO (GZO) transparent electrodes of GZO/Pt/GZO (GPG) multilayers on glass and flexible plastic substrates. Pt-inserted GZO electrodes showed remarkably decreased resistivity, even though the thickness of the Pt layer was only a few nm. However, the optical transmittance of the GPG electrodes was degraded with increasing thickness of the Pt layer. The structural, optical, and electrical properties of GZO film and GPG multilayered transparent electrodes on glass substrates were largely affected by post- annealing conditions such as the ambient and temperature. Post-annealing in a N2 ambient was the most effective treatment for achieving high optical transmittance and low electrical resistivity of the GZO films and GPG structure. Good optical transmittance of 78% and electrical resistivity of 3.5 x 10(-3) Ω·cm of the GZO electrode were obtained for the 4-nm-thick Pt insertion layer and post-annealing at 400 °C. In addition, touch sensor devices were fabricated by using GPG structures and flexible plastic substrates. The touch sensor devices exhibited a capacitance ratio of 1.4 between the two states before and after fingertip touching.
RESUMEN
Through silicon via (TSV) technology is becoming a mainstream method of building 3-dimensional integrated circuits (3D IC). In particular, TSV Cu CMP is a critical process to remove excess Cu and makes a planar surface which requires a removal rate higher than 5 microm/min and a dishing lower than 0.3 microm. This paper focuses on the development of a new self-alignment method using dimples on the TSV Cu back surface. We tried to find an application potential of a bump-dimple structure for self alignment using a pretest tool of a solder ball array structure. Chemical-mechanical planarization (CMP) aided dimple etching is carefully studied as a key solution for deep and uniform dimple formation. The experiment shows that CMP is an excellent process to generate a clean oxide surface and a clear dishing on the Cu TSV, resulting in a seed for etching. Finally, etching realizes a uniform dimple depth of 7 microm to 9 microm in spite of changes of via diameter from 10 microm to 50 microm after only 15 sec etching.
RESUMEN
Sapphire (alpha-Al2O3) is an important ceramic material that is widely used in substrate material for electronics. We investigate the chemical reaction layer on a sapphire wafer using X-ray photoelectron microscopy (XPS) and atomic force microscopy (AFM). The frictional characteristics of sapphire chemical mechanical polishing (CMP) was studied using in-situ friction force monitoring system. From XPS analysis and AFM experiment, a chemically-reacted layer was verified on the sapphire surface through a chemical reaction between the sapphire and chemicals in a slurry. During sapphire CMP, the friction force mainly depended on the applied pressure. The material removal efficiency per unit friction energy in sapphire CMP was 6.18 nm/kJ.