DOI: 10.29026/oes.2022.210005 Charge carrier dynamics in different crystal phases of CH 3 NH 3 PbI 3 perovskite Efthymis Serpetzoglou 1 *, Ioannis Konidakis 1 , George Kourmoulakis 1, 3 , Ioanna Demeridou 1,4 , Konstantinos Chatzimanolis 2 , Christos Zervos 2 , George Kioseoglou 1,3 , Emmanuel Kymakis 2 and Emmanuel Stratakis 1,3,4 * Despite that organic-inorganic lead halide perovskites have attracted enormous scientific attention for energy conversion applications over the recent years, the influence of temperature and the type of the employed hole transport layer (HTL) on the charge carrier dynamics and recombination processes in perovskite photovoltaic devices is still largely unex- plored. In particular, significant knowledge is missing on how these crucial parameters for radiative and non-radiative re- combinations, as well as for efficient charge extraction vary among different perovskite crystalline phases that are in- duced by temperature variation. Herein, we perform micro photoluminescence (μPL) and ultrafast time resolved transi- ent absorption spectroscopy (TAS) in Glass/Perovskite and two different Glass/ITO/HTL/Perovskite configurations at temperatures below room temperature, in order to probe the charge carrier dynamics of different perovskite crystalline phases, while considering also the effect of the employed HTL polymer. Namely, CH 3 NH 3 PbI 3 films were deposited on Glass, PEDOT:PSS and PTAA polymers, and the developed Glass/CH 3 NH 3 PbI 3 and Glass/ITO/HTL/CH 3 NH 3 PbI 3 archi- tectures were studied from 85 K up to 215 K in order to explore the charge extraction dynamics of the CH 3 NH 3 PbI 3 or- thorhombic and tetragonal crystalline phases. It is observed an unusual blueshift of the bandgap with temperature and the dual emission at temperature below of 100 K and also, that the charge carrier dynamics, as expressed by hole injec- tion times and free carrier recombination rates, are strongly depended on the actual pervoskite crystal phase, as well as, from the selected hole transport material. Keywords: transient absorption spectroscopy; μ-photoluminescence; variable temperature; perovskite crystalline phases; hole transport layer; charge carrier dynamics Serpetzoglou E, Konidakis I, Kourmoulakis G, Demeridou I, Chatzimanolis K et al. Charge carrier dynamics in different crystal phases of CH 3 NH 3 PbI 3 perovskite. Opto-Electron Sci 1, 210005 (2022).   Introduction Organic-inorganic lead halide perovskites have attracted scientific attention during the last decades. Their ex- traordinary properties made them, one of the major competitors for next-generation optoelectronic applica- tions, such as photovoltaics 1−3 , light-emitting devices 1 , photodetectors 4,5 , random lasers 6 , and light-emitting di- odes 7,8 . In particular, the power conversion efficiency (PCE) of lead halide perovskite solar cells (PSCs) has been increased from ~4% up to 26.7% within a decade or   1 Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), Herakleio 70013, Greece; 2 Electrical and Computer Engineering Department, Hellenic Mediterranean University, Herakleio 71004, Greece; 3 Department of Materials Science and Technology, University of Crete, Herakleio 70013, Greece; 4 Department of Physics, University of Crete, Herakleio 70013, Greece. *Correspondence: E Serpetzoglou, E-mail: eserpe@iesl.forth.gr; E Stratakis, E-mail: stratak@iesl.forth.gr Received: 6 April 2021; Accepted: 19 August 2021; Published online: 21 April 2022 Opto-Electronic Science Original Article 2022, Vol. 1, No. 4 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. © The Author(s) 2022. Published by Institute of Optics and Electronics, Chinese Academy of Sciences. 210005-1