1 Introduction

This project consists of two drift-diffusion simulation codes that are largely based on the same code but do have their own use: For steady-state simulations, including ions in stabilized scans, \(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} SimSS}}\) ¹ is most suited. One can easily define a voltage range that should be used, a light intensity, etc. and it will compute a current-voltage characteristic. \(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} SimSS}}\) can also extract the typical performance characteristics when simulating a solar cell, or compare a computed current-voltage characteristic with an experimental one and show the error. Simulations are typically fast.

For transient simulations, \(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} ZimT}}\), ² German for cinnamon, is much more suited and it can also do more simulations, including steady-state ones, transient photovoltage, impedance spectroscopy, etc. Much of the functionality that \(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} SimSS}}\) has is also included in \(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} ZimT}}\). However, \(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} ZimT}}\) reads-in a list of times, voltages and generation rates supplied by the user (see section 3.5) and then computes the resulting current density and voltage. For example, by supplying an AC voltage of varying frequency, \(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} ZimT}}\) can be used to simulate an impedance spectroscopy experiment. Alternatively, one can switch the light intensity from on to off and monitor how the current develops over time, just like a transient photocurrent experiment.