Seminars take place on Thursdays at 10:15
in the EE-IS lecture hall
(Wilhelm-Conrad-Röntgen Campus, Kekuléstr. 5, 1. Floor, room 227),
coffee and cookies are available 15 minutes before the seminar.
Please note that are exceptions from this rule, which are highlighted in the seminar plan.
next EE-IS seminar
Igal Levine (Weizmann Institute)
Can we use time-resolved measurements to get Steady-State Transport data for Halide Perovskites ?
on 19.7.2018, 10:15, coffee at 10:00
in the Silicon PV Seminar room
(WCRC Adlershof, 12.8, Kekulestr. 5, 12489 Berlin)
Organic-inorganic metal Halides Perovskites (HaPs) have emerged as a new and promising class of materials for photovoltaic applications, with unprecedented small-area cell efficiencies already exceeding 22%, approaching those of state-of-the-art photovoltaic devices based on inorganic single crystals. Diffusion lengths and, thus, the directly related mobility and lifetime values of the electronic carriers provide crucial insight into electronic device behavior. This holds especially so for halide perovskite (HaP)-based cells, and measuring, understanding and assessing the importance of these parameters has become a major issue in HaP studies.
Here we address the question whether deriving steady-state diffusion lengths from pulsed experiments justified and provide a clear answer when it is and when great care should be taken or their use avoided. Thus, we compare derived HaP carrier diffusion lengths with actual, measured ones using the Steady State Photocarrier Grating (SSPG) method, under 1-sun equivalent steady state excitation. We propose and use a novel way to compare between pulsed and steady state measurements at different excitation intensities. Our results also provide new physical insights into the understanding of charge carrier recombination in HaP thin polycrystalline films, demonstrating that the dependence of the charge carrier diffusion lengths on excitation intensity in HaPs can be explained using a single type of recombination center model. With this model we show how we can reconcile between what would at first sight seem to be contradictory results from steady-state and pulsed excitation.
Location: EE-IS lecture hall (room 227), Kekuléstr. 5, WCRC Berlin-Adlershof,
Time: Monday 14:00