Microscopy cryostat system for exploring how intense THz pulses affect ultrafast photoluminescence dynamics in organic semiconductors and nanomaterials

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Exploring the dynamics of light emission from photoexcited materials provides unique insight into the fundamental nature of materials and can have significant impact on the development of new photonic device structures. Time-resolved photoluminescence (PL) is a common technique for studying transient light emission from materials illuminated by short laser pulses. Photoluminescence from semiconductors, organic materials, and nanomaterials is typically the result of electron-hole recombination from photoexcitations called excitons. In many cases, the build-up and decay times of light emission from a material can occur over picosecond time scales, requiring the use of ultrafast laser sources and measurement techniques in order to actually observe such fast processes. Factors that may influence the PL dynamics in materials include sample morphology, temperature, and the presence of high electric fields that tend to break apart the excitons and possibly quench the PL. We propose to use antenna coupling of intense terahertz (THz) pulses in order to achieve highly localized, picosecond-duration, high-amplitude electric-field transients in photoexcited materials and then study the effects of these THz-electric-field transients on the PL dynamics as a function of temperature. We already have extensive experience with terahertz pulses, nonlinear terahertz dynamics, and ultrafast time-resolved THz spectroscopy of organic semiconductors and nanomaterials. (We were the first lab in Canada to perform time-resolved THz spectroscopy experiments on materials, and the first lab in the world to use the technique for probing bandlike transport in organic semiconductors.) The microscopy cryostat system requested here will allow us to perform micrometer-spatially-resolved and ultrafast picosecond-time-resolved PL measurements on organic semiconductors and nanomaterials at low temperatures while simultaneously applying intense THz pulses to the samples. This approach, which has never been tried before, would provide a powerful new tool for probing the dynamics of light emission from materials and understanding exciton dissociation mechanisms in organic semiconductors and nanomaterials.