This presentation provides an overview of photophysical studies of quantum dots conducted in the context of solar energy conversion. A specific focus is on early time carrier dynamics investigated using a combination of optical and transient photocurrent (TPC) spectroscopies.   In TPC measurements, we incorporate quantum dots into a fast electro-optical switch triggered by femtosecond laser pulses and monitor photocurrent transients using a broadband sampling oscilloscope with the 10-to-40 ps time resolution.  Applying this approach, we can resolve early time processes observed prior to charge extraction from the quantum dots as well as later-time dynamics due to carrier relaxation within the spectrum of band-edge states and non-geminate recombination. We are also able to probe directly in the photocurrent the process of carrier multiplication wherein multiple excitons are generated by single photons. In addition, this method allows us to study the competition between charge extraction and Auger recombination as well as the effect of sample temperature and applied electric field on multiexciton yields.

Early time carrier dynamics in quantum dot solids studied by ultrafast photocurrent spectroscopy

251st National Meeting (2016)

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