Public Abstract

DE-SC0025401: Intrinsic charge transport and photoconducting properties of single crystalline halide perovskites

Award Status: Active

Institution: Rutgers, The State University of New Jersey, Piscataway, NJ
UEI: M1LVPE5GLSD9
PM: Mewes, Tim

Most Recent Award Date: 07/15/2026
Number of Support Periods: 3
PI: Podzorov, Vitaly

Current Budget Period: 08/15/2026 - 08/14/2027
Current Project Period: 08/15/2024 - 08/14/2027

Public Abstract

Intrinsic charge transport and photoconducting properties of single crystalline halide perovskites. V. Podzorov, Rutgers, the State University of New Jersey (Principal Investigator) Early success of metal-halide perovskites in solar cells, light-emitting diode and laser applications is impressive. However, comprehensive understanding of the electronic properties of these materials that dictate their behavior in semiconductor devices is still lacking. One aspect aggravating this situation is the overwhelming focus of the experimental research community on solution-coated polycrystalline perovskite films known to be significantly affected by chemical and morphological defects (grain boundaries, vacancies, chemical impurities, etc.). In spite of the practical importance of applied studies of such films, defects in this form of samples largely mask the fundamental properties and limitations of perovskites. Thus, the main objective of this project is to use high-quality, nearly defect-free perovskite single crystals, rather than polycrystalline/(semi)amorphous thin films, and comprehensively investigate the fundamentals of charge generation, conduction and recombination in these crystalline materials, necessary for gaining deeper fundamental insights into their intrinsic behavior and fundamental limitations in optoelectronic devices. The PI will use high-performance perovskite transistors based on large-area, single crystalline perovskites recently developed in the PI’s group at Rutgers University (V. Bruevich et al., The Intrinsic (Trap-free) Transistors Based on Epitaxial Single-crystal Perovskites, Adv. Mater., DOI:10.1002/adma.202205055 (2022)). In addition, the group has earlier developed an ultra-sensitive magneto-transport measurement technique, based on the famous Hall effect, that is an excellent methodology for investigating various aspects of charge photogeneration and flow in emergent semiconducting materials (Y. Chen, H. T. Yi, V. Podzorov, High-Resolution ac Measurements of the Hall Effect in Organic Field-Effect Transistors, Phys. Rev. Appl. 5, 034008 (2016)). The combination of these novel fabrication and characterization techniques forms the core expertise of the group, providing them with a competitive edge in reaching the above research objective. In addition, these techniques will be supplemented by a powerful suite of surface/structural analysis and theoretical modeling, available via internal and external collaborations. The project consists of the following thrusts: - Growth of crystalline perovskites and fabrication of high-performance transistors to be used as a vehicle for the fundamental research. - Investigating charge conduction in these devices, occurring in a nearly defect-free environment, which will be carried out as a function of temperature, magnetic field, illumination, as well as ambient gaseous environment. - Studies of a photo-Hall effect in these single-crystal perovskites, a technique where charges are generated in a material by illuminating devices with visible light. - Investigating photoconductivity, a phenomenon of a material becoming electrically conductive under illumination, performed here in devices not limited by defects. - Investigating the effect of strain on the charge conduction properties of these materials, as induced, for instance, by mechanical bending of ultra-thin, flexible crystals. The potential impact of the project is fundamental. The work will lead to a deeper and more comprehensive understanding of the intrinsic charge conduction properties and performance limitation in perovskites of different crystal structures relevant to energy and microelectronic applications. This knowledge can ultimately help designing better materials with tailored or enhanced physical properties. The project will lead to ubiquitous availability of high-quality perovskite samples and devices for the research community, so that other groups can apply their investigative techniques to such defect-free samples. It will contribute to further development and optimization of several sophisticated experimental methodologies, including crystal growth of complex materials, fabrication of transistors, and in-situ strain-variable measurements. The broader impact of the project is also very significant. It will directly or indirectly contribute to several cutting-edge areas of modern science and technology, including microelectronics, solar cells, flexible electronics, strain engineering, and nanoscale surface characterization. The project will significantly stimulate theoretical work, because the experimentally obtained intrinsic (not affected by defects) properties of materials are the most valuable kind of input that theory strives to receive from experimentalists. The interdisciplinary nature of the project will foster interactions between solid-state physicists, surface scientists, and chemists, thus providing excellent educational and human resource opportunities.

Intrinsic charge transport and photoconducting properties of single crystalline halide perovskites.

V. Podzorov, Rutgers, the State University of New Jersey (Principal Investigator)

Early success of metal-halide perovskites in solar cells, light-emitting diode and laser applications is impressive. However, comprehensive understanding of the electronic properties of these materials that dictate their behavior in semiconductor devices is still lacking. One aspect aggravating this situation is the overwhelming focus of the experimental research community on solution-coated polycrystalline perovskite films known to be significantly affected by chemical and morphological defects (grain boundaries, vacancies, chemical impurities, etc.). In spite of the practical importance of applied studies of such films, defects in this form of samples largely mask the fundamental properties and limitations of perovskites.

Thus, the main objective of this project is to use high-quality, nearly defect-free perovskite single crystals, rather than polycrystalline/(semi)amorphous thin films, and comprehensively investigate the fundamentals of charge generation, conduction and recombination in these crystalline materials, necessary for gaining deeper fundamental insights into their intrinsic behavior and fundamental limitations in optoelectronic devices.

The PI will use high-performance perovskite transistors based on large-area, single crystalline perovskites recently developed in the PI’s group at Rutgers University (V. Bruevich et al., The Intrinsic (Trap-free) Transistors Based on Epitaxial Single-crystal Perovskites, Adv. Mater., DOI:10.1002/adma.202205055 (2022)). In addition, the group has earlier developed an ultra-sensitive magneto-transport measurement technique, based on the famous Hall effect, that is an excellent methodology for investigating various aspects of charge photogeneration and flow in emergent semiconducting materials (Y. Chen, H. T. Yi, V. Podzorov, High-Resolution ac Measurements of the Hall Effect in Organic Field-Effect Transistors, Phys. Rev. Appl. 5, 034008 (2016)). The combination of these novel fabrication and characterization techniques forms the core expertise of the group, providing them with a competitive edge in reaching the above research objective. In addition, these techniques will be supplemented by a powerful suite of surface/structural analysis and theoretical modeling, available via internal and external collaborations.

The project consists of the following thrusts:
- Growth of crystalline perovskites and fabrication of high-performance transistors to be used as a vehicle for the fundamental research.
- Investigating charge conduction in these devices, occurring in a nearly defect-free environment, which will be carried out as a function of temperature, magnetic field, illumination, as well as ambient gaseous environment.
- Studies of a photo-Hall effect in these single-crystal perovskites, a technique where charges are generated in a material by illuminating devices with visible light.
- Investigating photoconductivity, a phenomenon of a material becoming electrically conductive under illumination, performed here in devices not limited by defects.
- Investigating the effect of strain on the charge conduction properties of these materials, as induced, for instance, by mechanical bending of ultra-thin, flexible crystals.

The potential impact of the project is fundamental. The work will lead to a deeper and more comprehensive understanding of the intrinsic charge conduction properties and performance limitation in perovskites of different crystal structures relevant to energy and microelectronic applications. This knowledge can ultimately help designing better materials with tailored or enhanced physical properties. The project will lead to ubiquitous availability of high-quality perovskite samples and devices for the research community, so that other groups can apply their investigative techniques to such defect-free samples. It will contribute to further development and optimization of several sophisticated experimental methodologies, including crystal growth of complex materials, fabrication of transistors, and in-situ strain-variable measurements.

The broader impact of the project is also very significant. It will directly or indirectly contribute to several cutting-edge areas of modern science and technology, including microelectronics, solar cells, flexible electronics, strain engineering, and nanoscale surface characterization. The project will significantly stimulate theoretical work, because the experimentally obtained intrinsic (not affected by defects) properties of materials are the most valuable kind of input that theory strives to receive from experimentalists. The interdisciplinary nature of the project will foster interactions between solid-state physicists, surface scientists, and chemists, thus providing excellent educational and human resource opportunities.