In Situ Light Irradiated Perovskite NMR

Descripción del proyecto

Que se haga la luz: reducción de la fotodegradación en unas celdas fotovoltaicas prometedoras

La disminución de los costes y la mejora de la eficiencia han sido las piedras angulares de la investigación en celdas fotovoltaicas durante decenios. Las celdas fotovoltaicas de perovskita han tomado el mundo gracias a su notable grado de eficiencia. En la actualidad, las celdas fotovoltaicas de perovskita van camino de ofrecer lo que el mundo quiere y necesita en términos de coste y eficiencia, pero se enfrentan a desafíos debido a su fotodegradación. Por ello, se necesitan unos métodos mejores de caracterización de la fotodegradación «in situ» para un diseño racional que supere este obstáculo. En el proyecto iSLIP-NMR, financiado con fondos europeos, se desarrolla una forma de arrojar luz sobre los mecanismos de degradación utilizando la espectroscopia de resonancia magnética nuclear «in situ», una potente técnica de caracterización que guarda relación con los escáneres de resonancia magnética utilizados en los hospitales. El trabajo del proyecto podría dar lugar a celdas fotovoltaicas que resistan el paso del tiempo y de la luz.

Objetivo

Widespread adoption of photovoltaics for clean, plentiful and renewable energy requires cheap, efficient and long-lasting solar cells; hybrid perovskite solar cells are promising candidates but suffer from light-induced degradation under operational conditions. Chemical understanding of the photodegradation processes is required to develop stable materials, but is challenging to obtain with existing techniques. Here we propose to study perovskite degradation under in situ light irradiation using high-resolution solid-state NMR. Solid-state NMR is an atomic-scale, element-specific probe of local structure which has recently been shown to provide important information on perovskite systems, however new methodology is required to perform in situ light irradiation. Significantly, many photodefects will be present at low concentrations and/or localised at surfaces; in order to observe these by NMR, in situ light irradiation will be combined with dynamic nuclear polarisation (DNP), whereby the greater polarisation of unpaired electrons boosts the NMR signal. The project is split into three parts: (1) observation of major perovskite photodegradation products under in situ light irradiation that do not require additional sensitivity; (2) adaptation of DNP NMR to perovskites to observe surface passivating species; and (3) combined DNP-enhanced, in situ light-irradiated NMR to observe minor and/or surface photodefects. All three parts represent innovative methodological advances and will provide key chemical information on perovskite structures and degradation processes to guide future development of stable solar cells. The combination of myself and the Emsley lab is ideal to perform this project, through which I will develop the advanced technical and non-technical research skills required for the project to be succesful. The fellowship will expand my international network and result in wide-reaching research output, which will establish me as an independent researcher.