BEGIN:VCALENDAR VERSION:2.0 PRODID:Icfo X-PUBLISHED-TTL:P1W BEGIN:VEVENT UID:69d255c75e6f0 DTSTART:20230324T103000Z SEQUENCE:0 TRANSP:OPAQUE LOCATION:ICFO Mir Puig Homage and Online (Teams) SUMMARY:ICFO | MARIIA KRAMARENKO CLASS:PUBLIC DESCRIPTION:To mitigate the energy and climate crisis we are already facing and address the increasing energy consumption\, it is essential to foster energy transition strategies. The energy transition success largely depen ds on being able to transform the global energy sector from fossil fuel-ba sed to neutral or zero carbon dioxide emission sources. A decades-long stu dy of photovoltaics has produced several generations of solar energy conve rsion technologies that do not emit greenhouse gases or air pollution when they operate. However\, considering the sun is our planet's most abundant energy source\, when compared to fossil fuels\, the use of photovoltaics is still very limited. In such a transition from fossil fuels to photovolt aics\, it is essential to enhance affordability combined with high efficie ncy. In recent years\, perovskite solar cells have emerged as the most pro minent thin-film PV technology to provide high efficiency simultaneously a t a low cost. In this thesis\, we study perovskite-based solar cells and o ptical routes to maximise their power conversion efficiency. The theoretic al limit for converting sunlight into electricity by the photovoltaic effe ct was first established by William Shockley and Hans-Joachim Queisser in 1961 based on the principle of detailed balance. According to their work\, a solar cell can reach a limiting efficiency if all loss mechanisms are e liminated and the fluorescence quantum yield is equal to unity. The conver sion efficiency for all PV technologies is still considerably lower than t he Shockley &ndash\; Queisser efficiency limit\, but perovskite-based ones have demonstrated outstanding optoelectronic properties and high fluoresc ence quantum yields\, which may help get their maximum PV efficiency close r to such limit. In this thesis\, we provide several optical routes to opt imise the photovoltaic parameters of perovskite solar cells\, placing a sp ecial emphasis on the open circuit voltage by studying its relation to the absorption and emission of photons by the perovskite layer.\nThis thesis is organised into five chapters. Chapter 1 serves as an introduction\, whi ch includes a discussion of the current world energy demand and available photovoltaic technologies\, focusing more on the ones based on perovskite materials. The Shockley &ndash\; Queisser efficiency limit and power loss mechanism are also described in this chapter. In Chapter 2\, we analyse th e relationship between open circuit voltage and fluorescence quantum yield in perovskite-based solar cells\, both theoretically and experimentally\, and discuss the observed deviation from the predicted behaviour. Chapter 3 describes the new fabrication method of high-quality perovskites with lo w band gaps and big grain size is described. The two-step compact PbI2-tem plated growth method facilitated the achievement of solar cells with high fluorescence quantum yield and open circuit voltage. In Chapter 4\, we dev eloped a model and optimisation algorithm to find the optimum photonic str uctures to optically enhance the photovoltaic parameters for different ban d gap perovskite solar cells. Theoretical results from this chapter sugges t that a simple dielectric multilayer placed on top of the substrate of th e solar cell can simultaneously improve the open circuit voltage and short circuit current\, resulting in a relative gain of power conversion effici ency larger than 4%. Finally\, in Chapter 5\, the concept theoretically st udied in the previous chapter is experimentally implemented. The dielectri c multilayer is fabricated and placed on top of a perovskite solar cell\, resulting in an enhanced open-circuit voltage and power conversion efficie ncy.\n \;\nThesis Director: Prof Dr. Jordi Martorell DTSTAMP:20260405T122959Z END:VEVENT END:VCALENDAR