Coherent Light Emitters From Solution Chemistry: Inorganic II–VI Nanocrystals and Organometallic Perovskites

Semiconductor lasers are the prime example of compact coherent light-emitters having developed into mature technologies with ubiquitous presence in applications across much of the optical spectrum. Yet there are reasons to explore new materials, both to access those parts of the spectrum not fully accessible by these inorganic single crystal devices, while exploring alternative high throughput methods of material synthesis. In this paper, we focus on solution-processed thin film nanocrystal materials as possible candidates to expand the material repertoire of semiconductor lasers. We review work on inorganic II-VI compound colloidal quantum dots and nanoplatelets and then present recent work in our laboratory on organometallic perovskites, which have gained significant attention quite recently by their promise as high performance photovoltaic solar cells. We concentrate on fundamentals of the optical gain and means of integrating the solution grown nano/microcrystalline thin films into high-Q cavities to identify prime challenges ahead to turn these intriguing materials into viable laser devices.