Project Details
Projekt
Correlating Defect Densities with Recombination Losses in Halide-Perovskite Solar Cells (CREATIVE)
Subject Area
Experimental Condensed Matter Physics
Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
Term
since 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 506699658
Perovskite solar cells (PSCs) are showing great promise as a photovoltaic technology on the brink of maturity, with laboratory efficiencies comparable to high-efficiency silicon solar cells. In addition to their excellent performance as photovoltaic absorber layers, perovskites also allow tuning of their band gap by altering their composition, thereby becoming an attractive proposition for use in tandem cells. However, state-of-the-art devices for these applications show substantial voltage losses with respect to their thermodynamic limit, due to non-radiative recombination losses associated with distributions of defect densities within the perovskite bulk and its interfaces with the transport layers. Accurate characterization of the magnitudes of these defect densities is therefore of paramount importance to minimize the voltage losses in these devices. However, their estimation using traditional techniques (such as space-charge limited current (SCLC) and capacitance methods) are hampered by the large geometric capacitance of the thin-film PSCs, which hides the response from the defect density and provides an upper limit of resolution below which the defect density cannot be known.In this project, we tackle this problem by improving the resolution power of these techniques by moving from vertical (sandwich) devices to lateral devices. This change in geometry reduces the geometric capacitance of the device and gives several orders higher resolving power in magnitude to determine the actual defect density distribution in the device. This analysis will be complemented with a novel photoluminescence method to determine recombination losses at all bias points along the current-voltage curve, in addition to accurate determination of non-radiative recombination lifetimes and diffusion lengths determined from a suite of methods, both in the time domain (transient-photoluminescence (tr-PL), transient photovoltage (TPV) and transient photocurrent (TPC)) and frequency domain (Intensity-modulated photocurrent spectroscopy (IMPS), impedance spectroscopy (IS)). The quality of analysis of these methods will be heightened by the use of drift-diffusion simulations and Bayesian parameter estimation methods to allow for accurate parameter estimation from experimental data. This characterization strategy will lead to a fundamental correlation between experimentally-measured defect densities, lifetimes and the voltage losses, which has not been achieved so far.
DFG Programme
Priority Programmes
