Towards Self-scrubbing Stable and Scalable Perovskite Solar Cells

Lead Research Organisation: Imperial College London
Department Name: Dept of Chemistry

Abstract

Perovskite solar cells (PSCs) show unprecedented levels of efficiency for such easy to process solar cells, and are higher than those of most common, but more expensive, silicon cells. They have an excellent potential to provide low-cost solar electricity. Spectacular impact is expected but is hindered by poor stability of the perovskite phase and concerns about the use of lead and especially its potential release into the environment. Lead is also a relatively highly regulated element. In this proposal, our team of leading chemists, materials scientists, device physicists and theorists, will address these issues through an integrated collaborative study. Building on our previous work we will improve the understanding of the key mechanisms responsible for PSC degradation, by exploring new perovskites, morphologies and stabilisation by the use of additives. The link between defects (structural imperfections) and PSC performance/stability will be investigated experimentally and using state-of-the-art modelling techniques. The approach will provide a sound basis for predictive guidelines for perovskite formulation to enable stable environmentally benign, inexpensive PV units for mass use. Among the most intriguing aspects of perovskite materials are the high efficiency of charge pair photo-generation and the long lifetime of these charges. We will use new ultrafast timescale spectroscopic techniques to obtain new insights concerning the dynamics of the perovskite photo-excited states. We will address issues of potential heavy metal contamination, in the event of PSC failure (and water ingress) by studying new lead-free perovskites as well as by developing new heavy metal self-scrubbing scaffolds within lead- and tin-containing PSCs. A new aerosol-assisted film deposition approach for fabrication of large area, high performance, stable and environmental safe PSCs will result. Our ambition is to provide prototype environmentally safe, demonstration, large area PSCs with enhanced operational stability that could be mass produced and have power conversion efficiencies exceeding 20%. A successful outcome to this project would provide improved fundamental understanding of the interplay between perovskite composition and device performance and new PSCs that would bring about the large-scale deployment of perovskite photovoltaics for CO2-free electricity generation closer.

Publications

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Hu Y (2018) Identifying and controlling phase purity in 2D hybrid perovskite thin films in Journal of Materials Chemistry A

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Lanzetta L (2020) Stability of Lead and Tin Halide Perovskites: The Link between Defects and Degradation. in The journal of physical chemistry letters

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Macdonald TJ (2021) Phosphorene Nanoribbon-Augmented Optoelectronics for Enhanced Hole Extraction. in Journal of the American Chemical Society

 
Description Key research highlights and outcomes to date include development of lead free perovskite solar cells, understanding the factors influencing stability and (iii) interrogating charge transfer phenomena in perovskite heterojunctions.
1) The realisation of lead free perovskite solar cells is a key change in the field. In this project, we have already demonstrated a >10% lead free perovskite solar cell based on Tin. This work has been published: Chemical Communications 57 (41), 5047-5050
2) We have elucidated the degradation mechanism of Tin based based perovskites. This work has been published in the high impact journal Nature Communications: Nature communications 12 (1), 1-11 and also highlighted in the popular RSC magazine Chemistry World.
3) The light induced charge transfer processes in perovskite materials is fundamental to the operation of solar cell devices based on such materials. Herein we have investigated role of surface passivation and specific organic semiconductor perovskite surface interactions on the yields of photoinduced charge transfer. This work offers guidelines that can be employed to design and engineer new and improved perovskite materials for solar energy conversion systems. This work has been published: The Journal of Physical Chemistry Letters 12 (13), 3312-3320 and Journal of the American Chemical Society 143 (31), 12230-12243.
Exploitation Route Further grant funding targeted at delivering high performance (stability and efficiency) tin perovskite based optoelectronic devices including solar cells. A key focus will be the controlling both the chemical and mechanical stability of semiconducting perovskite films.
Sectors Electronics,Energy,Environment

 
Title Driftfusion 
Description First official release of Driftfusion. The recent application of lead-halide perovskites as an active layer material in thin film semiconductor devices including solar cells, light emitting diodes (LEDs), and memristors has motivated the development of several new drift-diffusion models that can include the effects of both mobile electronic and ionic charge carriers. Here, we present Driftfusion, a versatile simulation tool built for simulating one-dimensional ordered semiconductor devices with mixed ionic-electronic conducting layers. Driftfusion enables users to simulate devices with virtually any number of layers and with up to four charge carrier species (electrons and holes by default plus up to two ionic species). The time-dependent carrier continuity equations are fully-coupled to Poisson's equation enabling transient optoelectronic device measurement protocols to be simulated. In addition to the material parameters, users have direct access to adapt carrier transport, recombination and generation models as well as the system boundary conditions. Furthermore, a graded-interface approach circumvents the requirement for boundary conditions at material interfaces and enables interface-specific properties, such as high rates of interfacial recombination, to be introduced. 
Type Of Technology Software 
Year Produced 2020 
Open Source License? Yes  
URL https://zenodo.org/record/3670155
 
Title Driftfusion 
Description First official release of Driftfusion. The recent application of lead-halide perovskites as an active layer material in thin film semiconductor devices including solar cells, light emitting diodes (LEDs), and memristors has motivated the development of several new drift-diffusion models that can include the effects of both mobile electronic and ionic charge carriers. Here, we present Driftfusion, a versatile simulation tool built for simulating one-dimensional ordered semiconductor devices with mixed ionic-electronic conducting layers. Driftfusion enables users to simulate devices with virtually any number of layers and with up to four charge carrier species (electrons and holes by default plus up to two ionic species). The time-dependent carrier continuity equations are fully-coupled to Poisson's equation enabling transient optoelectronic device measurement protocols to be simulated. In addition to the material parameters, users have direct access to adapt carrier transport, recombination and generation models as well as the system boundary conditions. Furthermore, a graded-interface approach circumvents the requirement for boundary conditions at material interfaces and enables interface-specific properties, such as high rates of interfacial recombination, to be introduced. 
Type Of Technology Software 
Year Produced 2020 
Open Source License? Yes  
URL https://zenodo.org/record/3670154