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Title:	Electron beam-deposited nickel oxide as potential hole-transporting material for air-stable perovskite solar cell
Authors:	A.K. Mahmud Hasan (P75298)
Supervisor:	Md. Akhtaruzzaman, Assoc. Prof. Dr.
Keywords:	Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia Solar cell Perovskite materials
Issue Date:	17-Sep-2020
Description:	Perovskite materials have become the center of solar power-related research due to extreme efforts involved in preparing high-quality perovskite thin films in low cost process. The perovskite absorber generates electron-hole pairs once absorb sunlight and those charge carriers are transported by their corresponding charge carrier transport materials such as electron transport material (ETM) for electron transportation and hole transport material (HTM) for hole extraction. Nevertheless, hole extraction in inverted planar structure of PSCs has remained critical. Organic HTMs are very prone to destroy in presence of moisture and ultra violet light leading device degradation. Moreover, they require high purification and tedious synthesis process. On the other hand, inorganic HTM are very promising in regards to device stability as well as performance. In this study, inorganic NiOx has been considered as an efficient HTM for designing devices with inverted PSCs by the optimized deposition technique with highest material utilization and low temperature condition. The numerical simulation performance study aids in pre-assessment on device performance based the material properties. Thin-film material properties, device fabrication, photovoltaic performance, and device degradation analysis of PSCs have been conducted to satisfy the objectives of this research study. The detailed structural, morphological, optical, electrical characterizations and device performance have been investigated by XRD, PL, PYS, AFM, FESEM, SEM, UV-VIS, light current-voltage (LIV) tester and EQE (external quantum efficiency) measurement system. Initially, a Solar Sell Capacitance Simulator (SCAPS-1D) software has been used to evaluate the photovoltaic performance of PSC devices with NiOx as HTM considering the existing material properties of NiOx besides defect density at an interface layer of the device. Moreover, state-of-the-art Finite-Difference-Time-Domain (FDTD) software has been used to measure device performance in relation to absorption losses at each layer of the device. A simple electron-beam physical vapor deposition (EBPVD) technique has been selected for producing dense, highly pure, and uncontaminated NiOx films at low temperatures instead of complex techniques that require highly elevated temperature. A NiOx film with a thickness of 20 nm has been deposited as an HTM for inverted PSCs by using a NiOx pallet onto a fluorine-doped tin oxide (FTO)-coated glass substrate by EBPVD with a chamber vacuum pressure of 4.6×10-4 Pa. The PSCs were fabricated as glass/FTO/NiOx (HTM)/CH3NH3PbI3/PC61BM/BCP/Ag structures with as-deposited, annealed and annealed-UV/O3 treated NiOx films. The NiOx film substrates were exposed to UV/O3 stripper for ozonization after annealing (500 °C for 30 min in muffle furnace). Under one sun (100 mW/cm2) illumination, the as-deposited NiOx PSCs in a 0.16 cm2 active area showed a high-power conversion efficiency (PCE) of 13.20% with a short-circuit current density (Jsc) of 17.9 mA/cm2, an open-circuit voltage (Voc) of 0.95 V, and a fill factor (FF) of 0.77. The PSC devices of the same area with annealed NiOx as HTM showed a high PCE of 13.24% with a Jsc of 17.16 mA /cm2, Voc of 0.98 V, and FF of 0.78. Device with annealed-UV/O3 treated NiOx HTM exhibited 10.93% PCE with Jsc of 15.46 mA /cm2, Voc of 0.97 V, and FF of 0.73. PSCs devices with as-deposited, annealed and annealed-UV/O3 treated NiOx as HTM retained 72.72%, 76.96% and 72.46% of their initial efficiency in ambient conditions, respectively at 28th day of fabrication. This study highlights that annealed NiOx film as HTM offered better stable and efficient inverted PSC.,Ph.D.
Pages:	166
Publisher:	UKM, Bangi
Appears in Collections:	Solar Energy Research Institute / Institut Penyelidikan Tenaga Suria (SERI)

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