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

混合卤化物钙钛矿材料使薄膜光伏发电发生了革命性的变化，在几年的研究中，光伏效率已飙升至22%。混合卤化物钙钛矿的光电性能几乎可以与最成功的无机半导体(如砷化镓)相媲美，也为发光二极管(LED)和激光提供了一个有趣的平台。对于激光应用，人们认为钙钛矿可以克服/避免有机增益介质施加的典型限制和损失机制，例如由于三重激子和极化子而导致的三重单重态湮灭或吸收。因此，钙钛矿为实现一种可以在低温下从溶液中制备的电动半导体激光器提供了新的希望。钙钛矿激光器甚至具有覆盖530-610 nm之间的光谱区域的潜力，这是现有的无机半导体增益介质，如GaInN或AlGaInP等在室温下难以解决的。虽然杂化卤化物钙钛矿可以通过一些简单的低温技术来制备，但它们的化学敏感性严重限制了它们的图案化利用现有的湿化学光刻技术。到目前为止，混合卤化物钙钛矿在光电子和光子应用中的巨大潜力还没有被部分释放，因为缺乏合适的通用纳米制备技术，这需要在最大程度的控制和最高的精度下直接在钙钛矿层中形成谐振器结构、波导等。在NIPLAS中，我们打算使用热纳米压印(NIL)来直接图案化混合卤化物钙钛矿半导体。虽然我们已经在MAPbI3中进行了一些有希望的前期工作，但对于NIL在MAPbI3和这一家族中的其他代表材料中的印迹机制和比较研究还缺乏深入的认识。因此，NIPLAS项目旨在揭示杂化卤化物钙钛矿中热零离子的基本机制。此外，我们还打算为钙钛矿型光电子器件开发利用热零化来图案化光子结构的令人兴奋的机会。我们将把重点放在钙钛矿激光器上，但可以预期，在这个项目中获得的见解也将对其他基于钙钛矿的器件，如LED，太阳能电池，光电探测器等具有普遍的相关性。NIPLAS项目的主要目标是：1.确定混合卤化物钙钛矿半导体中热压印的基本机制2.根据钙钛矿的热机械性质确定压印过程的极限3.研究热压印对钙钛矿结构和光电性能的影响4.压痕光子纳米结构在低阈值钙钛矿激光器中的设计与应用

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