Insights into charge carrier dynamics in organo-metal halide perovskites: from neat films to solar cells

Abstract

Organo-metal halide perovskites have recently obtained world-wide attention as promising solar cell materials. They have broad and strong light absorption along with excellent carrier transport properties which partially explain their record power conversion efficiencies above 22%. However, the basic understanding of the underlying physical mechanisms is still limited and there remain large discrepancies among reported transport characteristics of perovskite materials. Notably, the carrier mobility of perovskite samples either in thin films or within solar cells obtained using different techniques can vary by up to 7-8 orders of magnitude. This tutorial review aims to offer insights into the scope, advantages, limitations and latest developments of the techniques that have been applied for studying charge carrier dynamics in perovskites. We summarize a comprehensive set of measurements including (1) time-resolved laser spectroscopies (transient absorption, time-resolved photoluminescence, terahertz spectroscopy and microwave conductivity); (2) electrical transient techniques (charge extraction by linearly increasing voltage and time-of-flight); and (3) steady-state methods (field-effect transistor, Hall effect and space charge limited current). Firstly, the basics of the above measurements are described. We then comparatively summarize the charge carrier characteristics of perovskite-based neat films, bilayer films and solar cells. Finally, we compare the different approaches in evaluating the key parameters of transport dynamics and unravel the reasons for the large discrepancies among these methods. We anticipate that this tutorial review will serve as the entry point for understanding the experimental results from the above techniques and provide insights into charge carrier dynamics in perovskite materials and devices.

Photonics and Optoelectronics of 2D Metal‐Halide Perovskites

“…Copyright 2015, American Chemical Society. g) Emission wavelength, h) carrier mobility, i) carrier diffusion length, and j) photoluminescence quantum yield of 2D perovskite and other 2D covalent semiconductors …”

Influence of Urbach Energy, Temperature, and Longitudinal Position in the Active Layer on Carrier Diffusion Length in Perovskite Solar Cells

“…Solar cells based on hybrid halide perovskites of the structure AMX3, where A is an organic cation, M is a metal cation, and X is a halide anion, have achieved a power conversion efficiency (PCE) higher than 22 %. [14] Stranks et al [15] have used transient absorption and photoluminescence-quenching measurements to determine the electron-hole diffusion lengths, diffusion constants, and lifetimes in the mixed halide (CH 3 NH 3 PbI 3 -xClx) and triiodide (CH 3 NH 3 PbI 3 ) perovskite absorbers. [6][7][8][9] In contrast to organic solar cells (OSCs), the photon absorption in the active layer of PSCs excites electron and hole pairs which do form excitons but with very small binding energy; only a few meV, and hence can easily be dissociated even at room temperature.…”

Tailoring electrical property of the low-temperature processed SnO2 for high-performance perovskite solar cells

“…Metal halide perovskites have stirred researchers' great interests in the photovoltaic field and achieved rapid development in the recent decade due to the high absorption coefficient, tunable band gaps, long carrier diffusion length, and low trap density [1][2][3][4][5][6]. Perovskite solar cells (PSCs), as the star candidates of photovoltaic devices, have realized a power conversion efficiency (PCE) up to 22.7%, comparable with conventional CdTe or CIGS analogues [7].…”