Organic photovoltaics and organic-perovskite tandem solar cells

A summary of the project:
In recent years there have been massive advances with metal halide perovskite photovoltaics. One of the key properties of perovskite PV, is that they can generate very high open-circuit voltages with relatively wide band gaps. This enables their use in "multi-junction" cells, where the wide band gap perovskite cell, is combined with a narrower band gap cell, which is either perovskite or a traditional PV material such as silicon. Recently however, organic photovoltaics have made significant strides forward in terms of absolute efficiency, and organic cells employing low band gap "non-fullerene" electron acceptors can now deliver up to 18% efficiency. This implies that an opportunity exists to combine wide band gap perovskites, with narrow band gap organics, and deliver a very high efficiency light weigh thin-film perovskite-on-organic tandem technology. In this project, Nicky will be developing and investigating organic PV cells, which are matched for combining with perovskites in tandem devices. In the first instance he will investigate different charge extraction layers in OPV cells, and determine the impact of tuning the energy level alignment in such devices. He will progress to deliver improved efficiency and also integrate the devices into complete tandem cells.

Brief description of the context of the research including potential impact;
There is significant research efforts related to perovskite PV and organic PV, and this project will contribute to those overall fields of research. Oxford PV, a local company advancing new PV technology, is planning to launch its first manufactured product, perovskite-on-silicon tandem cells, mid next year. There is also significant academic and industrial effort on all perovskite thin-film technologies, and flexible organic PV technologies. This project here is working on what could be a future generation PV technology, combines aspects of organic and perovskite technologies, and could be transferable to industry on a 3 year time scale.

Aims and objectives;
To understand the impact of and develop new materials for improved stability and efficiency of organic PV cells, and the integration into perovskite-on-organic tandems.

Novelty of the research methodology;
We will be using a combination of thin-film deposition methodologies, including sputter coating, atomic layer deposition and thin-film thermal evaporation, employing the presently being installed EPSRC Advanced Functional Materials Cluster Deposition Facility. We will also employ Ultraviolet Photoelectron Spectroscopy, presently being ordered to combine with the cluster tool.

Alignment to EPSRC's strategies and research areas:
This project falls within the EPSRC's Physical Sciences growth area, Materials for Energy Applications, on "Synthesis, characterisation and theoretical understanding of functional materials to be used in energy applications," and, "includes fundamental studies into potential materials for photovoltaics (PV), and semiconductors." The Productive Outcome, will be the introduction of "the next generation of innovative and disruptive technology" for PV, with transformation "to a sustainable society," and increased National Resilience through "energy security". Solar Technologies is a maintain area, where the strategic focus of EPSRC is that "There will be greater focus on thin films and new materials (e.g. potentially game-changing perovskites)."