Nanopatterning of hybrid perovskites by thermal nanoimprint for perovskite lasers – (NIPLAS)

• Applicants: Professor Dr. Thomas Riedl; Professorin Dr.-Ing. Hella-Christin Scheer
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; Synthesis and Properties of Functional Materials
• Term: from 2018 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 398045707

Hybrid halide perovskites have revolutionized thin-film photovoltaics as efficiencies have skyrocketed to levels >22% within a few years of research. With optoelectronic properties almost at par with the most successful inorganic semiconductors such as GaAs, hybrid halide perovskites also state an intriguing platform for light emitting diodes (LEDs) and lasers. For laser applications, there is the vision that perovskites may overcome/avoid the typical limitations and loss mechanisms imposed by organic gain media, such as triplet-singlet annihilation or absorption due to triplet excitons and polarons. As such, perovskites seed a new promise for the realization of an electrically operated diode laser that can be prepared from solution at low temperatures. Perovskite lasers even bear the potential to cover the spectral region between 530-610 nm, which is difficult to address at room temperature with established inorganic semiconductor gain media, e.g. GaInN or AlGaInP etc. While hybrid halide perovskites can be prepared by a number of facile, low-temperature techniques, their chemical sensitivity severely limits their patterning via established wet-chemical lithography techniques. As of yet, the tremendous potential of hybrid halide perovskites for optoelectronic and photonic applications has not been unlocked partially because of the lack of suitable versatile nanopatterning techniques, which are required to create resonator structures, waveguides etc. directly into perovskite layers with a maximum level of control and utmost precision. In NIPLAS we intend to use thermal nanoimprint (NIL) to directly pattern hybrid halide perovskite semiconductors. While we have conducted some promising preliminary work on NIL in MAPbI3, insights about the imprint mechanism and comparative studies of NIL in MAPbI3 and other representatives of this family of materials are lacking.As such, the project NIPLAS aims to unravel the fundamental mechanisms underlying thermal NIL in hybrid halide perovskites. Furthermore, we intend to exploit the exciting opportunities of patterning photonic structures by thermal NIL for perovskite based optoelectronic devices. We will focus our efforts on perovskite lasers, but it can be expected that the insights gained within this project will also be of general relevance for other perovskite based devices like LEDs, solar cells, photodetectors, etc.Taken together, the main objectives of the NIPLAS project are:1. To identify the fundamental mechanism of thermal imprint in hybrid halide perovskite semiconductors 2. To identify the limits of the imprint process depending on the thermo-mechanical properties of the perovskite 3. To study the effect of thermal imprint on the structural and optoelectronic properties of the perovskite4. To design and apply imprinted photonic nanostructures for low-threshold perovskite lasers

• DFG Programme: Research Grants