Electrical Methods to Elucidate Charge Transport in Hybrid Perovskites Thin Films and Devices

Abstract

The panchromatic light absorption and excellent charge carrier transport properties in organo lead halide perovskites allowed to achieve an unprecedented power conversion efficiency in excess of 25 % for thin film photovoltaics fabrication. To understand the underlying phenomena, various comprehensive set of optical and electrical techniques have been employed to investigate the charge carrier dynamics in such devices. In this perspective, we aim to summarize the electrical transport properties of perovskite thin films by using (i) impedance spectroscopy (IS), (ii) space charge limited current (SCLC), (iii) field‐effect transistors (FETs) and (iv) time‐of‐flight (TOF) methods. We have deliberated various equivalent circuit used to model the perovskite solar cells by means of IS. The SCLC technique provide vital electrical parameters such as mobility, activation energy, traps density and distribution, carrier concentration, density of states, etc. The TOF technique measures mobility as a primary parameter while the FETs configuration provide a valuable insight into the in‐plane charge transport in perovskites thin films. We believe that these notable understanding will provide insights into charge carrier dynamics in perovskite materials and devices.

Low-Temperature-Processed Perovskite Solar Cells Fabricated from Presynthesized CsFAPbI3 Powder

“…We performed thermal admittance spectroscopy at varying temperatures to reveal the shallow and deep defect density and trap energy distribution within the band gap of CsFAPbI 3 -based PSCs. , Briefly, dark capacitance–frequency ( C – f ) measurements were performed at different temperatures on the CsFAPbI 3 -based fabricated PSCs from the presynthesized powder without applying a bias voltage (Figures S9 and S10). The frequency ( f ) ranges from 20 to 10 6 Hz.…”

N-Bromosuccinimide as an Interfacial Alleviator for Br/I Exchange in Perovskite for Solar Cell Fabrication

“…To unravel the role of NBS on the defect state and high value of shunt resistance achieved, thermal admittance spectroscopy (TAS) was performed (Figure A–C). , We measured the capacitance–frequency ( C – f ) curve at room temperature (Figure A) and variable temperature (Figure S12A,B); identical behaviors of the capacitance were noted. The plateau in the intermediate frequency (IF) range corresponds to the dielectric relaxation in the perovskites that can be described by the geometrical capacitance per unit area C g = εε 0 / L (ε and ε 0 refer to the dielectric constant and the permittivity of the vacuum, respectively; L is the layer thickness).…”

Evaluating the Capacitive Response in Metal Halide Perovskite Solar Cells

“…The trap density of states N T as a function of E ω (Figure 13c) can be evaluated through the Eq. 18: [19,112] …”