Perovskite (MaPbI3) Aging Signal in Millimeter Wave Transients
Description
Hybrid organic-inorganic perovskite (HOIP) exhibit low cost, versatility in fabrication methods and possess good application potential because of high power conversion efficiency. Methylammonium lead Iodide (MAPbI3) with quartz substrate thin film sample (glass encapsulated) was obtained from NC State University have been used to obtain millimeter wave (mmw) transient response at probe frequencies of 140 and 150 GHz from CIDO and BWO sources respectively. The HOIP film was produced at NC State University on May 02, 2017. In our time-resolved TR-mmWC apparatus, the glass-covered sample was excited by a 1KHz triggered 532 nm laser beam with a width of 0.7 ns with maximum fluence 10 microJoules per sq. cm and a spot size of 10mm. Transient datasets were recorded using a 6 GHz input bandwidth digitizer after amplifying Schottky detector registered radiofrequency (RF) signal due to differential absorption of the passing millimeter wave from source (normal to sample) at 140 and 150 GHz through sample. Signal averaging was done 4096 times and data were collected on 4 different dates spanning 2, 6, and 8 months and 1 year from date of manufacture. Data attached here represent the complete set of aging signals collected over 0 to about 40,000 hours after production of the MAPbI3 thin film in 2017. Dataset comprises of 120 GHz and 150 GHz probe. Generally, an increase in radiative and trap-assisted recombination lifetimes of charge carriers was noted, and a decrease in amplitudes were also noted after fitting data by double exponential. The fits are obtained by adding a second excitation to account for double peaks. Data attached are CSV files with column 1 being the pump-probe delay time (second), and column 2 being voltage response (V). The low noise amplifier gain of 15.527 dB must be accounted for June 28, 2017, December 18, 2017, and February 21, 2018 datasets and a gain of 15.91 dB must be accounted for the data file obtained on May 03, 2018 to yield the actual voltages. Examples: File with name “NCSU-Perovskite-CIDO-6-140GHz-3-26-RF-Average-FullLaserPower-June-28-2017” is obtained using a solid state IMPATT cavity oscillator operated at 140 GHz with 10 mW output power and after illuminating the sample with full laser power (22.14 mW). Filename: “NCSU-Perovskite-BWO-150GHz-1KHz-FullLaserPower-Dec-18-2017” is the average transient for the same sample obtained on December 18, 2017 but using an electrovacuum BWO as probe source that is operated at 30% power level to transmit the same output power ~ 10 mW and further use of only about 0.32 mW for probing (in all cases using a beam splitter). A code to handle the data, compute, and plot the trends of step responses of the 120- and 150 GHz combined set for GPR based machine learning is added in this repository (Note: some filenames in the code need to be adjusted with the additional extension added in order to avoid repeating names, and directory structure need to be modified)
Files
Steps to reproduce
Sample was prepared at NCSU following Zhao et al., "High Efficiency Solutio-Processes Planar Perovskite Solar Cells with a Polymer Hole Transport Layer", Adv. Ener. Mat., 2015, 5, 1401855; Time Resolved spectroscopy procedure performed at NCCU reference Biswadev Roy, et al., "A Time-Resolved millimeter wave conductivity (TR-mmWC) apparatus for charge dynamical properties of semiconductors, Review of Scientific Instruments, Vol. 89, 104704, 2018