Non-fullerene Acceptors (NFAs) have gathered a great deal of interest for use inorganic photovoltaics (OPVs) due to recent breakthroughs in their power conversion efficiency and other advantages they offer over their Fullerene-based counterparts. In this work, a new promising non-fullerene polymer acceptor, PF5-Y5, have been studied using density functional theory and time-dependent density functional theory; and the effects that oligomer length, geometry relaxation and exchange-correlation interaction has on the exciton binding energies (the difference between optical and fundamental energy gaps) have been investigated. Both the fundamental and optical gaps are significantly affected by the choice of functional (i.e., the description of the exchange-correlation interaction). However, it does not appear to significantly impact obtained exciton binding energies as the effects of the fundamental and optical gaps cancel each other out. Both the fundamental and optical energy gap are shown to slightly reduce as a function of the oligomer length (~0.1 - 0.3 đđ reduction for each repeated monomer). As both gaps are reduced by a similar amount per repeated monomer, they counteract each other and the total effect that oligomer length has on the exciton binding energy is very low. Geometry relaxation and thermal effects showed the largest impact on the fundamental gap and exciton binding energy, with their combined effect resulting in a ~0.5 đđ reduction in binding energy. / Non-Fullerene Acceptorer (NFAs) har rönt stort intresse för anvĂ€ndning i organiska solceller (OPVs) pĂ„ grund av genombrott pĂ„ senare tid gĂ€llande deras effektomvandlingsverkningsgrad och en mĂ€ngd andra fördelar som de erbjuder jĂ€mfört med sina fullerene-baserade motsvarigheter. I det hĂ€r arbetet har en ny lovande polymer-acceptor, PF5-Y5, studerats med hjĂ€lp av tĂ€thetsfunktionalteori (DFT) och tidsberoende tĂ€thetsfunktionsteori (TD-DFT). Effekterna som oligomerlĂ€ngd, geometri-avslappning och utbytes-korrelations-interaktion har pĂ„ exciton-bindningsenergin (skillnaden mellan optiska ochfundamentala energigapen) har Ă€ven undersökts. BĂ„de erhĂ„llna vĂ€rden för det fundamentala och optiska gapet pĂ„verkas avsevĂ€rt av valet av funktional (dvs. beskrivningen av utbytes-korrelations-interaktionen). Valet av funktional verkar dock inte nĂ€mnvĂ€rt pĂ„verka erhĂ„llna vĂ€rden för excitonbindningsenergin dĂ„ effekterna frĂ„n det fundamentala och optiska gapen till stor del tar ut varandra. BĂ„de det fundamentala och optiska energigapet minskar som en funktion av oligomerlĂ€ngden (~0.1 - 0.3 đđ minskning för varje upprepad monomer). Eftersom bĂ„da energigapen minskar ungefĂ€r lika mycket för varje upprepad monomer sĂ„ motverkar de till stor grad varandra; och den totala effekten som oligomerlĂ€ngd har pĂ„ exciton-bindningsenergin förblir lĂ„g. Strukturell relaxation (eng: geometry relaxation) och termiska effekter visade sig ha störst pĂ„verkan pĂ„ det fundamentala energigapet och exciton-bindningsenergin, och deras sammanlagda effekt ledde till en ~0,5 đđ reduktion i bindningsenergi.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kau-88646 |
| Date | January 2022 |
| Creators | Almén, Anton |
| Publisher | Karlstads universitet, Institutionen för ingenjörsvetenskap och fysik (from 2013) |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | Swedish |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf, application/pdf |
| Rights | info:eu-repo/semantics/openAccess, info:eu-repo/semantics/openAccess |
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