Nanostructure enhanced photovoltaic devices

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Tezin Türü: Doktora

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Metalurji ve Malzeme Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2015

Öğrenci: PANTEA AURANG

Danışman: HÜSNÜ EMRAH ÜNALAN

Özet:

There are mainly three generations of solar cells that have been categorized by considering their efficiency and manufacturing cost. Although lots of investigations and research is going on in this field, but the first generation solar cells are most commercially available solar cells. First generation solar cells consist of single and multi-crystalline silicon (Si), which has been doped typically by phosphorus and boron in a p-n junction configuration. Si is non-toxic, relatively low cost and naturally abundant semiconducting material, which make it quite beneficial to be employed in microelectronics and photovoltaic industry. In general, Si solar cells contain, a Si active layer sandwiched with antireflection layer and metallic contacts. Solar cells fabricated from solar grade Si shows high efficiency; however, the impurity level should be kept in minimum. Moreover, cell production process consists of high energy consuming steps such as co-firing of the contacts in metallization step (900°C) and antireflective coating deposition via plasma enhanced chemical vapor deposition (PECVD) which necessitate high temperatures (400°C) and vacuum. Improving performance of conventional Si solar cells and decreasing costs by consuming less expensive materials is an important challenge that should be overcome. Employing nanostructured materials instead of bulk or thin film components can be a promising route, which recently inspired many scientists. Nanowires that are synthesized via low-cost and solution-based methods can be utilized in any of the cell components to provide distinct advantages, which is the main theme of this thesis. In this regard, independently, vertically aligned zinc oxide nanowires are utilized as antireflection coatings, random silver nanowire networks are used as top electrodes and vertically aligned Si nanowires on ultrathin Si wafers are used as the active layer in crystal Si solar cells.