Organic solar cells - Design, Synthesis, and characterization of a novel electron acceptor

Organiske solceller - design, syntese og karakterisering af ny elektronaccepter

Andersen, Thomas Rieks

4. term

Chemistry, Master (Scient)

2010

2010-08-05

66

Formålet med afhandlingen var at designe et nyt elektronacceptor-oligomer med lavt båndgab for at forbedre elektronstransport i organiske solceller. Et lavt båndgab kan øge sollysabsorptionen, og en elektronacceptor hjælper med at trække elektroner fra donormaterialet. Strategien var at sætte elektron-tilbagetrækkende grupper på thiophen-enheder koblet til en kendt elektronacceptor-kerne, udvalgt ud fra båndgab og LUMO-niveau (lowest unoccupied molecular orbital), som er centrale for solcelleydelse. Den valgte kerne var N,N'-bis(2,2'-octyldodecyl)-naphthalene-1,8,4,5-bis(dicarboximide), med 3,3'-dinitro-2,2'-dithiophen som sidekæde. Det planlagte slutmolekyle kunne ikke syntetiseres på grund af problemer med dannelsen af 2-octyldodecyl-1-amin og med Stille-koblingsreagenset (en tværkoblingsmetode). I stedet blev et beslægtet stof, N,N'-bisoctyl-2,6-dithiophenenaphthalene-1,8,4,5-bis(dicarboximide), fremstillet ved Stille-kobling. Det blev karakteriseret med UV/vis-spektroskopi (lysabsorption) og testet i organiske solceller med poly(3-hexylthiophene) som elektrondonor. En effektivitetsgrad på 0,084 % blev opnået; efter varmebehandling (annealing) faldt effektiviteten til 0,055 %.

This thesis aimed to design a new electron-accepting oligomer with a low band gap to improve charge transport in organic solar cells. A low band gap can help absorb more sunlight, and an electron acceptor promotes moving electrons away from the donor material. The plan was to attach electron-withdrawing groups to thiophene units connected to a known electron-acceptor core, chosen based on measured band gaps and the position of the LUMO (lowest unoccupied molecular orbital), both key parameters for solar-cell performance. The selected core was N,N'-bis(2,2'-octyldodecyl)-naphthalene-1,8,4,5-bis(dicarboximide), with 3,3'-dinitro-2,2'-dithiophene as the side chain. The intended final molecule could not be synthesized due to difficulties forming 2-octyldodecyl-1-amine and issues with the Stille coupling reagent (a cross-coupling method). Instead, a related compound, N,N'-bisoctyl-2,6-dithiophenenaphthalene-1,8,4,5-bis(dicarboximide), was obtained via Stille coupling. Its properties were characterized by UV/vis spectroscopy (light absorption) and tested in organic solar cells using poly(3-hexylthiophene) as the electron donor. The device reached a power conversion efficiency of 0.084%; after annealing (thermal treatment), the efficiency decreased to 0.055%.

[This abstract was generated with the help of AI]

organic solar cells ; electron acceptor

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