ABSTRACT
We compared nickel oxide (NiO x ) deposited by thermal evaporation and that deposited by the spin-coating process, for use in the hole transport layers of inverted planar perovskite solar cells (PSCs). Spin-coating deposition for NiO x HTL has been widely used, owing to its simplicity, low cost, and high efficiency. However, the spin-coating process has a technical limit to depositing a large-area uniformly. In contrast, thermal evaporation fabrication has a low price and is able to produce uniform and reproducible thin film. Hence, the chemical states, energy band alignment, surface morphologies, and microstructures of NiO x deposited by spin coating and thermal evaporation were analyzed. The PSC with NiO x HTL deposited by thermal evaporation showed a higher power conversion efficiency of 16.64% with open circuit voltage 1.07 V, short circuit current density of 20.68 mA cm-2, and a fill factor of 75.51% compared to that of PSC with spin-coated NiO x . We confirmed that thermal evaporation can deposit NiO x to give a better performance as a HTL with higher reproducibility than spin-coating.
ABSTRACT
Surgical decompression for cervical radiculopathy includes anterior cervical discectomy and fusion, anterior or posterior cervical foraminotomy, and cervical arthroplasty after decompression. The aim of this study was to evaluate the usefulness of a CO2 laser in posterior-approach surgery for unilateral cervical radiculopathy. From January 2006 to December 2008, 12 consecutive patients with unilateral cervical radiculopathy from either foraminal stenosis or disc herniation, which was confirmed with imaging studies, underwent posterior foraminotomy and discectomy with the use of a microscope and CO2 laser. For annulotomy and discectomy, we used about 300 joules of CO2 laser energy. Magnetic resonance imaging (MRI) was used to evaluate the extent of disc removal or foraminal decompression. Clinical outcome was evaluated by using visual analogue scale scores for radicular pain and Odom's criteria. For evaluation of spinal stability, cervical flexion and extension radiographs were obtained. Single-level foraminotomy was performed in 10 patients and two-level foraminotomies were performed in 2 patients. Preoperative radicular symptoms were improved immediately after surgery in all patients. No surgery-related complications developed in our cases. Postoperative MRI demonstrated effective decompression of ventral lesions and widened foraminal spaces in all cases. There was no development of cervical instability during the follow-up period. Posterior foraminotomy and discectomy using a microscope and CO2 laser is an effective surgical tool for unilateral cervical radiculopathy caused by lateral or foraminal disc herniations or spondylotic stenosis. Long-term follow-up with radiographs showed no significant kyphotic changes or spinal instability.
