On the upscaling of organic solar cells based on non-fullerene acceptors
- Autores: Enrique Pascual San José
- Directores de la Tesis: Mariano Campoy Quiles (dir. tes.), Marco Stella (dir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2020
- Idioma: español
- Tribunal Calificador de la Tesis: Emilio J. Palomares Gil (presid.), Esther Barrena Villas (secret.), Peter Levermore (voc.)
- Programa de doctorado: Programa de Doctorado en Ciencia de Materiales por la Universidad Autónoma de Barcelona
- Materias:
- Enlaces
- Tesis en acceso abierto en: TESEO
- Resumen
Over the last years, organic photovoltaic technology (OPV) has drawn the attention of both the scientific and industrial communities due to their increasing performances, currently over 18%. These high efficiencies have been achieved thanks to the chemical development of the small molecular acceptors, also known as non-fullerene acceptors (NFA). Besides the efficiency, NFA-based OPV offers colour and transparency tuneable properties, low embodied energy, and good long-term stability. These unique properties make OPV a suitable technology for their commercialisation as a part of building-integrated photovoltaic systems (BIPV) or for powering the so-called Internet of Things (IoT).
This thesis covers some of the critical issues that need to be addressed for OPV to become a truly competitive technology. Firstly, we studied theoretically the strategies for tuning the colour appearance of OPV films. With the aid of an optical model and a genetic algorithm, we predicted the characteristics that photoactive materials should have in order to exhibit a desired colour. The use of non-fullerene acceptors (NFA) for the photoactive blends turned out to be the most effective colour-tuning strategy. As a result, NFAs-based devices were intensively studied in this thesis. Moreover, as an intermediate step towards a large printing scale, the doctor blade technique was employed for most of this thesis work.
Due to their synthetic flexibility, there are many NFAs and their processing conditions that are worth studying. Two examples of combinatorial screening using high throughput techniques are given. First, 1D gradients are applied to devices based on NFAs and polythiophene (P3HT), one of the cheapest and most studied polymers. 1D gradients enabled the fabrication of more than 1000 blade-coated devices with controlled variations in thickness or post-annealing temperature at the photoactive layers. For the most efficient system, we studied and ranked the sensitivity of the different manufacturing parameters. Second, we extended this to 2D gradients and explored both low bandgap polymers and NFAs. A simple method was developed based on controlled and simultaneous variations of the parameters of interest. With the aid of co-local optoelectronic characterisation techniques, 2D optimisation maps enable fast identification of the optimum thickness and blend composition values. Long term stability was also studied on selected devices, as a relevant factor for OPV upscaling, together with manufacturing fully roll-to-roll modules.
Transparency is another relevant characteristic feature that could enable OPV integration into the potential photoactive windows of the future. Semitransparent laser-patterned modules were fabricated with a NFA that contributes to extend the blend optical absorption up to the near-infrared region. With the aim of developing a sustainable manufacturing process, modules were manufactured following preferences of large-scale printing industry including non-halogenated solvents, air processing and low energy consumption. In summary, in this thesis we provide new insights into the upscaling of NFAs based OPV that pave the way towards an efficient transfer from record lab-devices to fully solution-processed modules.
