Research Blogs
Characterization Suite 4.5 helps researchers get more from Paios, Phelos and Litos
Characterization Suite 4.5 enhances the software environment for Paios, Phelos and Litos, helping researchers move faster from measurement to interpretation. With new post-processing tools, expanded measurement capabilities, improved stability workflows and a stronger 64-bit software foundation, the release supports more efficient OLED, solar cell, photodetector and ageing studies.
Reverse-bias Stressing of Perovskite Solar Cells
This study shows that reverse-bias in perovskite solar cells can trigger degradation even before breakdown occurs. Rather than immediate shunting, milder reverse-bias stress leads to progressive recombination-driven performance loss and reversible dark-spot formation, highlighting a key commercialization challenge under realistic operating conditions.
Light Conversion using Perovskite Quantum Dots
This tutorial presents the main properties of quantum dots and gives an example of how to characterize films with embedded quantum dots using angular resolved spectroscopy.
Stability Testing and Electronic Characterization of Kesterite Solar Cells for Indoor Applications
Fluxim presents advanced stability testing and electronic characterization techniques for kesterite solar cells. Learn how these tools enhance efficiency and reliability, making them ideal for indoor applications. Discover breakthroughs in renewable energy research!
Aging and Characterization of High-Bandgap Perovskite Solar Cells
Explore how advanced material and optoelectrical characterization techniques uncover the degradation mechanisms in high-bandgap perovskite solar cells. Discover the impact of temperature on aging, insights from electrical characterization, and the significance of parallel stressing for statistical validation.
Space Charge Limited Current (SCLC) and Charge Carrier Mobility in Organic Semiconductors
Discover how charge carrier mobility is measured in organic and perovskite semiconductors. This guide explains the Space Charge Limited Current (SCLC) method, with its key advantages, limitations, and applications.
How to Improve Measurement Accuracy of LED and PV Devices with a Common Electrode
Non-metalized contact pads and shared electrodes can undermine the accuracy of solar cell and LED measurements due to high contact resistance, distorting current-voltage (IV) curves and resulting in incorrect maximum-power-point (MPP) and open-voltage circuit (Voc) values. However, solutions exist: metallizing contact pads with gold or silver can reduce resistance issues, and avoiding common electrodes in multi-pixel designs can further enhance measurement accuracy, leading to improved reliability and efficiency in solar cells and LEDs.
Angular Resolved Photoluminescence and Electroluminescence of light emitting materials
Setfos can analyze angular-dependent PL data collected by Phelos to get information about the properties of an organic emitter, such as the orientation of the dipoles and the width of the emission zone. With this analysis, we are able to optimize the characteristics of our OLEDs for high EQEs.
Estimation of Charge Carrier Mobility in Solar Cells: An Introduction to CELIV
Dive into the world of mobility in solar cells, and explore how CELIV measurements help determine charge carrier mobility in thin-film solar cells like perovskite and organic solar cells. Learn about various CELIV techniques and their applications in this comprehensive research blog.
Quantification of trap states by thermally stimulated current in thin film solar cells
The performance of light-emitting (LEDs) and photovoltaic (PV) devices depends on the quality of the photoactive semiconductor material. The unintentional introduction of defects in the semiconductor material due to material impurities or during the fabrication process causes the deviation from optimal performance.
These defects are referred to as trap states, or in short “traps”, which are energetic states within the bandgap of a semiconductor. In general, traps can occur due to material impurities (in the bulk) or at the interfaces between layers of different materials.
In the following blog post, we will present how to characterize the trap states with the technique called thermally stimulated current (TSC). We also propose a method to reliably interpret the TSC results based on drift-diffusion simulations.
Influence of recombination rates on transient photoluminescence and efficiency of TADF OLEDs
OLEDs made by thermally-activated delayed fluorescence (TADF) materials as emitters promise an IQE of 100%. Here, we want to present an analysis of the influence of non-radiative recombination rates (knrs and knrt) on the device efficiency as well as how to determine them from experiments. As we will see, the knr rate influences PLQY, and consequently ELQY, hence the negative impact on EQE.
First, to determine the non-radiative decay rates, we need to extract the rates kf, krisc, and kisc by fitting transient photoluminescence (trPL) measurements of TADF films.
Fitting routine for a reliable transient photoluminescence simulation of perovskite films
Transient photoluminescence (trPL) characterization experiments allow to analysis charge carrier dynamics and identify the recombination channels of the device structure under investigation.
Useful information that can be extracted includes the quantification of radiative and non-radiative lifetimes, charge carrier extraction from differential lifetime computation, and the influence of the interfaces on the recombination mechanism. Fitting the experimental results with simulations further supports the analysis of the obtained data. However, qualitatively comparable fittings can be obtained with different sets of simulation parameters.
Using the fully-coupled, 1-dimensional optoelectronic simulation software Setfos, the trPL signal of a simple glass/perovskite structure was simulated and a routine is suggested to ascertain the reliability of the results. This routine is based on experimentally measured material properties and the analysis of the band diagram evolution during the photoluminescence transient. The validity of the simulated trPL is also recursively verified by fitting the decay with a bi-exponential function to extract the lifetimes of the recombination mechanisms.
How to quantify Non-radiative voltage losses and recombination in solar cells
The open-circuit voltage (Voc) is the electrical potential difference between the two terminals of a solar cell, when there is no external load applied, hence no electric current flows. Correspondingly, this means that, when a voltage equivalent to the Voc is applied to the terminals of the solar cell, the recombination current (Jrec, which typically follows a non-ideal diode equation) and the photocurrent (Jph, the current generated by illuminating the solar cell) are equal, hence the net current is zero (Jrec=Jph at V= Voc).
Solar cells often present also non-radiative recombination mechanisms, in addition to the radiative one, as a result of poor material quality and non-idealities. To increase the Voc and thus potentially the power conversion efficiency, it is necessary to minimize the ΔVoc,nrad. It is, therefore, necessary to quantify the total loss and determine its origin.
Electroluminescence (EL) and photoluminescence quantum yield (PLQY) allow to directly extract the ΔVoc,nrad for thin-film solar cells such as perovskite solar cells, kesterite, perovskite, organic, or quantum dot. solar cells.
After quantifying the losses, the combination of capacitance-voltage (CV), temperature-dependent voltage characteristics (JV-T), and capacitance-frequency (Cf-T) measurements are essential to identify the recombination mechanisms.
Optimize Hyperfluorescent and TADF OLEDs by Reducing Excitonic Loss Channels
We present a combined experimental/simulation analysis of a set of 4 OLEDs with 2 systematically varied guest dopants in the EML. A numerical electro-optical model is employed, demonstrating one consistent parameter set that describes both steady-state and AC characteristics of all devices. The model accounts for charge transport, trapping, polar layers, and excitonic loss processes. These are inducing an efficiency roll-off that can be correlated with the shape of the emission zone and the guest dopant concentrations. Furthermore, starting from the resulting parameter set, we show routes for optimized TADF OLDEs with a reduced roll-off.
Why Perovskite Solar cells with High Efficiency Show Small iV-curve Hysteresis
In many perovskite solar cells, hysteresis is observed between the forward and reverse current-voltage (IV) scans. This IV curve hysteresis can be problematic for the correct determination of the Power Conversion Efficiency (PCE). While the exact origin of the IV curve hysteresis has remained a topic of debate, it is now widely accepted that mobile ions are the principal cause. However, it is still the subject of ongoing debates about how exactly mobile ions influence the device operation.
In this blog, we are showing how a proper drift-diffusion simulation can help in understanding how mobile ions are affecting the JV characteristics of a perovskite solar cell.
Analysis of TADF OLED degradation by combining advanced characterization and simulation
Despite the success of OLED displays in commercial products, there are still issues regarding the efficiency and lifetime of these devices. It is of utmost importance to better understand the device physics in general and the origins of degradation in these OLEDs.
In this blog post, we show you an example for which we used our tools Paios and Setfos to understand device limitations and analyze the degradation mechanisms in state-of-the-art sky blue TADF OLED devices.