Polymer encapsulation of zinc oxide nanostructures for photodiode applications
| dc.contributor.advisor | Rauwel, Protima (advisor) | |
| dc.contributor.advisor | Rauwel, Erwan Yann (advisor) | |
| dc.contributor.author | Nagpal, Keshav | |
| dc.contributor.department | Institute of Forestry and Engineering | eng |
| dc.contributor.other | Nilsen, Ola (opponent) | |
| dc.contributor.other | Vilquin, Bertrand (opponent) | |
| dc.date.accessioned | 2024-07-04T06:36:46Z | |
| dc.date.available | 2024-07-04T06:36:46Z | |
| dc.date.defensed | 2024-08-26 | |
| dc.date.issued | 2024 | |
| dc.description | A Thesis for applying for the degree of Doctor of Philosophy in Engineering Sciences. | eng |
| dc.description | Väitekiri filosoofiadoktori kraadi taotlemiseks tehnikateaduse erialal. | est |
| dc.description.abstract | The research on photodiodes or devices that can detect UV light, is growing rapidly due to their wide range of applications in sensors, communication devices, solar cells and radiation detection. This work focuses on the development of novel cost-effective and energy-efficient hybrid photodiodes. These devices are composed of n-type (negative) and p-type (positive) semiconductor components that in our case, are ZnO nanorods and PEDOT:PSS / F8BT polymers, respectively. To make the fabrication cost-effective, hydrothermal synthesis was applied to grow ZnO nanorods that were then covered by polymers using spin coating. The performance of the photodiode is evaluated in terms of responsivity, sensitivity and response time. The photodiode energy efficiency was expressed through the external quantum efficiency and values as high as 2770% at low bias voltage of -2V, compared to other biases were obtained. The figures of merit were assessed as a function of the ZnO-nanorod growth conditions. The first step in the synthesis of the nanorod was the deposition of the seed layer using different cost-effective and eco-friendly alcoholic solvents. The absolute methanol seed layer solvents produced the best performing photodiodes. The seed layer (nucleation layer) was further studied in order to understand the surface defects they harbor that could improve or deteriorate the performance of the final photodiode. To that end, hydrothermal synthesis was applied to produce ZnO nanoparticles with the same seeding solvents. Their size, morphology as well as chemical and physical properties were investigated and correlated to the ZnO-nanorod properties. These studies showed a direct relationship between the alcoholic solvent used during the synthesis and the defect states present in the ZnO nanostructures that control and influence the opto-electrical properties and photodiode performances. This acquired knowledge enables the further development of a future cost-effective and energy-efficient photodiodes. | eng |
| dc.description.abstract | Fotodioode ja teisi UV-kiirgust tuvastavaid seadmeid arendatakse ja täiustatakse pidevalt, kuna need leiavad kasutust andurites, päikesepatareides ning side- ja erineva lainepikkusega kiirgust tuvastavates rakendustes. Doktoritöö keskendus uudsete, kulutõhusate ja energiasäästlike hübriidfotodioodide väljatöötamisele. Need seadmed koosnevad n- ja p-tüüpi pooljuhtkomponentidest, mis siinses uurimuses on vastavalt ZnO-nanovardad ja PEDOT: PSS / F8BT polümeerid. ZnO-nanovarraste kasvatamiseks rakendati hüdrotermilist sünteesi ning kaeti tsentrifuugimise teel polümeeriga. Fotodioodi jõudlust hinnati reageerimisvõime, tundlikkuse ja reaktsiooniaja järgi. Fotodioodi energiatõhusust väljendati välise kvantefektiivsuse kaudu: madala nihkepinge (–2 V) juures saadi väärtuseks kuni 2770%. Väärtusnäitajad hinnati funktsioonina ZnO-nanovarraste kasvutingimustest. Nanovarda sünteesi esimene samm oli külvikihi ladestamine, kasutades kulutõhusaid ja keskkonnasõbralikke alkohoolseid lahuseid. Metanooli külvikihi lahus andis parima jõudlusega fotodioodid. Täiendavalt uuriti pinnadefekte, mis võivad parandada või halvendada fotodioodi jõudlust. Sel eesmärgil rakendati hüdrotermilist sünteesi, et samade külvilahustega toota ZnO-nanoosakesi. Nende suurust, morfoloogiat ning keemilisi ja füüsikalisi omadusi võrreldi ZnO-nanovarda omadustega. Uuringud näitasid otsest seost alkohoolse lahuse ja defektide vahel ZnO-nanstruktuuris, mis mõjutab optoelektrilisi omadusi ja fotodioodide jõudlust. Saadud teadmised võimaldavad energiasäästlikke ja kulutõhusaod fotodioode edasi arendada. | est |
| dc.description.abstract | The work in the thesis is supported by the following financings. The Estonian State funds for the PhD, ETAG project COVSG, the center of Excellence project TK134, Horizon Europe NFFA pilot projects V220149MIEQ and V210108TIEQ. | eng |
| dc.description.sponsorship | The work in the thesis is supported by the following financings. The Estonian State funds for the PhD, ETAG project COVSG, the center of Excellence project TK134, Horizon Europe NFFA pilot projects V220149MIEQ and V210108TIEQ. | eng |
| dc.identifier.isbn | 978-9916-719-92-3 | |
| dc.identifier.issn | 2382-7076 | |
| dc.identifier.uri | http://hdl.handle.net/10492/9430 | |
| dc.identifier.uri | https://doi.org/10.15159/emu.139 | |
| dc.publisher | Estonian University of Life Sciences | eng |
| dc.relation.ispartofseries | Doctoral Theses of the Estonian University of Life Sciences | eng |
| dc.relation.ispartofseries | Eesti Maaülikooli doktoritööd | est |
| dc.rights | © Keshav Nagpal, 2024 | |
| dc.rights | info:eu-repo/semantics/openAccess | eng |
| dc.rights.uri | https://www.riigiteataja.ee/en/eli/ee/Riigikogu/act/519062017005/consolide | est |
| dc.subject | dissertations | eng |
| dc.subject | ZnO | |
| dc.subject | nanoparticles | eng |
| dc.subject | nanorods | eng |
| dc.subject | photodiode | eng |
| dc.title | Polymer encapsulation of zinc oxide nanostructures for photodiode applications | eng |
| dc.title.alternative | Tsinkoksiidi nanostruktuuride polümeerkapseldamine fotodioodrakenduste jaoks | est |
| dc.type | info:eu-repo/semantics/doctoralThesis | eng |
| dc.type.qualificationname | PhD |
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