Akademik Veri Yönetim Sistemi
Tezin Türü: Yüksek Lisans
Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Edebiyat Fakültesi, Kimya Bölümü, Türkiye
Tezin Onay Tarihi: 2020
Öğrenci: Tuğba. Hacıefendioğlu
Danışman: DEMET ASİL ALPTEKİN
Özet:One of the underlying reasons for the 33% theoretical limit of solar cells (Shockley–Queisser limit) is the losses originating from non-absorbed ultra violet and infrared regions of the solar spectrum. PbTe Quantum Dots-(QDs) and PbSe Nanorods-(NRs) are two of the intriguing nanocrystals which can be utilized to overcome the efficiency limit due to unique properties such as band gap tunability, large exciton Bohr radius and highly absorbing nature in ultra-violet and infrared regions. However, air instability and limited knowledge on the surface properties hinder their utilization in the field of optoelectronics. In this respect, a detailed understanding on the instability of those nanocrystals was presented and combinatorial passivation protocols based on engineering of the surface during the growth phase and solid-state ligand exchange process were developed. Dual passivation approach controls shape, ligand exchange rate, packing direction and mid gap state formation by dictating the {111}/ {200} facet ratio and yield solar cells with outstanding stabilities. Optical properties, stability behavior and band energies depend mainly on the aspect ratio of the NRs which is tuned by reaction parameters such as injection temperature, concentration of oleic acid and diphenylphosphine. We also found that the ligand choice was the key factor in improving the solar cell performance as affecting the thin film morphology by controlling the NR packing. Optimization of the cell fabrication protocols yields PbSe NR based solar cells with 80% external quantum efficiency (EQE) and 2.60% power conversion efficiency (PCE) and enhanced stability up to 54 days under inert atmosphere for the first time in literature.