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Fighting Health Hazards in Lead Halide Perovskite Optoelectronic Devices with Transparent Phosphate Salts

Pavao Roko Andricevic, László Forró, Endre Horvath, Márton Kollár, Xavier François Mettan, Lidia Rossi

Organic-inorganic lead halide perovskite (CH3NH3PbI3) solar cells have surpassed 25% power conversion efficiency, being ready for industrial-scale production of cheap photovoltaic (PV) panels. In this action, the major hurdle is its lead content, which in case of device failure, could be washed into the soil, entering the food chain. Since there is a zero tolerance on lead in the human organism, this health hazard is a critical obstacle for commercialization. Here, we propose a solution to this problem by incorporating phosphate salts (e.g., (NH4)(2)HPO4) in PV and other perovskite-based optoelectronic devices in various architectures. Phosphate salts do not react with CH3NH3PbI3 and do not alter its advantageous optoelectronic properties, but in a wet environment, they react immediately with lead, forming a highly insoluble compound, precluding this way the spread of lead into the environment. It is expected that this study will stimulate research, enabling lead halide perovskite solar cells to reach a similar environmental risk category as the commercially available, nonwater-soluble heavy metal-containing CdTe and gallium diselenide technologies.

AMER CHEMICAL SOC2021

Light-induced charge transfer at the CH3NH3PbI3/TiO2 interface-a low-temperature photo-electron paramagnetic resonance assay

Pavao Roko Andricevic, Philippe Bugnon, László Forró, Anastasiia Glushkova, Endre Horvath, Márton Kollár, Konstantins Mantulnikovs, Bálint Náfrádi, Lidia Rossi, Andrzej Sienkiewicz, Péter Szirmai

The performance of organic-inorganic metal halide perovskites-based (MHPs) photovoltaic devices critically depends on the design and material properties of the interface between the light-harvesting MHP layer and the electron transport layer (ETL). Therefore, the detailed insight into the transfer mechanisms of photogenerated carriers at the ETL/MHP interface is of utmost importance. Owing to its high charge mobilities and well-matched band structure with MHPs, titanium dioxide (TiO2) has emerged as the most widely used ETL material in MHPs-based photovoltaic devices. Here, we report a contactless method to directly track the photo-carriers at the ETL/MHP interface using the technique of low-temperature electron paramagnetic resonance (EPR) in combination with in situ illuminations (Photo-EPR). Specifically, we focus on a model nanohybrid material consisting of TiO2-based nanowires (TiO(2)NWs) dispersed in the polycrystalline methylammonium lead triiodide (MAPbI(3)) matrix. Our approach is based on observation of the light-induced decrease in intensity of the EPR signal of paramagnetic Ti3+ ( S = 1 / 2 ) in non-stoichiometric TiO(2)NWs. We associate the diminishment of the EPR signal with the photo-excited electrons that cross the ETL/MHP interface and contribute to the conversion of Ti3+ states to EPR-silent Ti2+ states. Overall, we infer that the technique of low-temperature Photo-EPR is an effective strategy to study the transfer mechanisms of photogenerated carriers at the ETL/MHP interface in MAPbI(3)-based photovoltaic and photoelectronic systems.

IOP PUBLISHING LTD2020

Photocatalytic Nanowires-Based Air Filter: Towards Reusable Protective Masks

László Forró, Endre Horvath, Caroline Lehmann, Lidia Rossi, Andrzej Sienkiewicz

In the last couple decades, several viral outbreaks resulting in epidemics and pandemics with thousands of human causalities have been witnessed. The current Covid-19 outbreak represents an unprecedented crisis. In stopping the virus' spread, it is fundamental to have personal protective equipment and disinfected surfaces. Here, the development of a TiO(2)nanowires (TiO(2)NWs) based filter is reported, which it is believed will work extremely well for personal protective equipment (PPE), as well as for a new generation of air conditioners and air purifiers. Its efficiency relies on the photocatalytic generation of high levels of reactive oxygen species (ROS) upon UV illumination, and on a particularly high dielectric constant of TiO2, which is of paramount importance for enhanced wettability by the water droplets carrying the germs. The filter pore sizes can be tuned by processing TiO(2)NWs into filter paper. The kilogram-scale production capability of TiO(2)NWs gives credibility to its massive application potentials.

WILEY-V C H VERLAG GMBH2020