How Non-Ohmic Contact-Layer Diodes in Perovskite Pinholes Affect Abrupt Low-Voltage Reverse-Bias Breakdown and Destruction of Solar Cells
Description
This repository contains essential data (largely current-voltage data and current-time data) to reproduce figures in the manuscript of the referenced article. Some code to plot raw data is provided, but we expect that users will be able to write their own simple plotting code. This repository contains a larger analysis code (Python via Jupyter Notebook) to produce the model curves that simulate the current-voltage curves of solar cells with various pinhole defects. This repository does not contain raw image data. Data: BCP_TLD_data.xlsx --- Current-voltage data from perovskite-free transport-layer diodes (TLDs) with BCP ETLs. Various HTLs are separated into sheets. SnOx_TLD_data.xlsx --- Current-voltage data from perovskite-free TLDs with SnOx ETLs. Various HTLs are separated into different sheets in the file. K21_13_PxD_JV.txt --- Current-voltage data from the solar cell recorded during video thermography (Fig. 1e) Folders: Fig_1b_JV_curves --- Current-voltage data for all cells in Fig. 1b of the manuscript. Fig_3G --- all TLD current-voltage data for 12 mm^2 and 200-micrometer diameter TLDs. Fig_3H --- all TLD current-time (fixed voltage) data for 12 mm^2 and 200-micrometer diameter TLDs. Fig_5B_12mm2 --- Current-voltage data from 12mm^2 cells Fig_5B_0.032mm2 --- Current-voltage data from 200-micrometer diameter cells Fig_5D --- Reverse-bias current-voltage scans from 200-micrometer diameter cells Fig_5E --- Forward-bias current-voltage scans from 200-micrometer diameter cells *after* reverse-bias scans Fig_5F --- Current-time data from fixed-voltage holds at -2.5 V on 200-micrometer diameter cells (data should be plotted with respect to the absolute start time in the filename after '*T*') SI_Figure_26 --- Current-voltage data from cells used for thermography imaging with metal (26C) and ITO (26F) top contacts. Codes: Double_Diode.ipynb The code Double_Diode.ipynb is used to calculate the current-voltage behavior of a solar cell with TLD-type pinholes. It is described in more detail here. The curves produced from this code assume TLD behavior derived by fitting the TLD data contained in 'BCP_TLD_data.xlsx' and 'SnOx_TLD_data.xlsx'. The "solar cell" area is define as an ideal p-i-n diode with characteristics taken from typical experimental values. The total model is described in the manuscript. Each diode is assigned a scaling factor of "phi", the area of the pinhole divided by the total area multiplied by the total number of pinholes. Pinholes are assumed circular and the size is defined by a pinhole radius (in micrometers) and then phi is calculated and applied to the total current density. We include the information on the fitting processes in the Supplementary Information.
Files
Steps to reproduce
Most of the data presented in this manuscript are raw current-voltage curves or current-time curves. The current was divided by the device area (11.9 cm2 for "full-size" cells or 0.032 mm2 for "miniature" cells) to get the current densities. Most of the images in the manuscript were presented without processing and thus represent the raw images, so raw image data are not provided here. Below is some guidance to use the double-diode equivalent circuit code. The code starts by creating the ideal solar cell using the ideal diode equation. Then, the user inputs the dark JV scans for the desired TLD materials. Then, the user verifies the fitted parameters for all desired TLDs to ensure the best JV curves are generated later on. The user will then determine the pinhole geometry and number of total pinholes. The results from this code are as follows: 0) Generating the ideal solar cell JV curve in the dark using the desired parameters and plotting experimental data to go along with it. 1) Verifying the fitted parameters for the inputted TLD dark JV files via two fitting methods ("current_iterative3" & "current_iterative4"). The first method incorporates the effects of fitting the ideal diode parameters, such as the saturation current density 'I0', Rseries, Rshunt, ideality factor 'n', and allows the user to determine boundary conditions for each fitted parameter. The second method follows the work of Kirchartz et. al., who employed a simpler exponential fit with terms for 'I0', 'n', 'b', and 'c' and also allows the user to set boundary conditions on the limits for these values. The plots verify the fits from both methods "3" and "4" and then moves on to apply the fitted parameters into the double diode equation. The total current density from both the ideal solar cell and the current density passing through the pinhole is calculated by taking the J_ideal (calculated from the ideal diode equation) and the corresponding active area and adding it to the current density extracted from fitting the TLD JV curves. The user determines the voltage range. This model assumes the JSC is a fixed value and the customization of the ideal cell can be done by altering the diode parameters prior to plotting the JV curves of the ideal cell with pinholes in it.
Institutions
- University of Colorado Boulder