JV editor (Steady state simulation editor)
If you click on the JV editor icon in figure 4.3, the JV editor window will open shown below in figure 4.4.
Inputs
This window can be used to configure steady state simulations. It does not matter if you are running a current-voltage sweep on a solar cell or an OFET. This plugin will steadily ramp the voltage from a start voltage to a stop voltage. The voltage will be applied to the contact which has been set to Change in the contact editor (see section 3.1.8). You can set the start voltage, stop voltage and step size. Use JV voltage step multiplayer to make the voltage step grow each step. The default is 1.0, i.e. no growth. It can be helpful to set the step multiplyer to a value larger than 1.0 if you want to speed up the simulation but it should not be increased past about 1.05 or the simulation may strugle to converge.
Outputs
The files produced by the JV simulation mode are given in table 10.1. As well as these files, by default OghmaNano will also write all internal simulation parameters to disk in the snapshots directory. This includes band structure, potential, carrier distributions, generation rates etc.. this equates to about 50 files per voltage step. You can read more about this in the simulation snapshots section, see 19.1. This can considerably slow down the simulation, the user can therefore decide how much is written to disk by using the Output verbosity to disk option this can be set to; Key results, which will result in only key files being written to disk;Nothing, which will result in no results being written to disk; Write everything to disk which will result in a all possible information being written to disk and Write everything to disk every nth step, which will only out comprehensive internal simulation write data every nth step.
| File name | Description | Notes |
|---|---|---|
charge.dat |
Charge density vs. voltage | |
jv.dat |
Current–voltage curve | |
k.csv |
Recombination constant k | |
sim_info.dat |
Simulation summary (calculated \(V_{oc}\), \(J_{sc}\), etc.); see §4.1.4 |
sim_info.dat
This is a json file containing all key simulation metrics such as \(J_{sc}\), \(V_{oc}\), and example sim_info.dat file is given below:
Steady state electrical simulation
In steady state electrical simulations such as performing a JV scan the sim_info.dat outputs the following parameters.
| Symbol | JSON token | Meaning | Units | Equ. | Ref |
|---|---|---|---|---|---|
| \(FF\) | ff | Fill factor | au | ||
| \(PCE\) | pce | Power conversion efficiency | % | ||
| \(P_{max}\) | P_max | Power at maximum power point | W | ||
| \(V_{oc}\) | V_oc | Open-circuit voltage | V | ||
| \(voc_{R}\) | voc_R | Recombination rate at \(P_{max}\) | |||
| \(jv_{voc}\) | jv_voc | JV data point at \(V_{oc}\) | |||
| \(jv_{pmax}\) | jv_pmax | JV data point at \(P_{max}\) | |||
| \(voc_{nt}\) | voc_nt | Trapped electron density at \(V_{oc}\) | m\(^{-3}\) | ||
| \(voc_{pt}\) | voc_pt | Trapped hole density at \(V_{oc}\) | m\(^{-3}\) | ||
| \(voc_{nf}\) | voc_nf | Free electron density at \(V_{oc}\) | m\(^{-3}\) | ||
| \(voc_{pf}\) | voc_pf | Free hole density at \(V_{oc}\) | m\(^{-3}\) | ||
| \(J_{sc}\) | J_sc | Short-circuit current density | A m\(^{-2}\) | ||
| \(jv_{jsc}\) | jv_jsc | Average charge density at \(J_{sc}\) | m\(^{-3}\) | ||
| \(jv_{vbi}\) | jv_vbi | Built-in voltage | V | ||
| \(jv_{gen}\) | jv_gen | Average generation rate | |||
| \(voc_{np}\) | voc_np | Carrier density product at \(V_{oc}\) | |||
| \(j_{pmax}\) | j_pmax | Current at \(P_{max}\) | A m\(^{-2}\) | ||
| \(v_{pmax}\) | v_pmax | Voltage at \(P_{max}\) | V |
| Symbol | JSON token | Meaning | Units | Equ. | Ref |
|---|---|---|---|---|---|
| \(\mu_{jsc}\) | mu_jsc | Avg. mobility at \(J_{sc}\) | m\(^2\) V\(^{-1}\) s\(^{-1}\) | ||
| \(\mu^{geom}_{jsc}\) | mu_geom_jsc | Geom. avg. mobility at \(J_{sc}\) | m\(^2\) V\(^{-1}\) s\(^{-1}\) | ||
| \(\mu^{geom\_micro}_{jsc}\) | mu_geom_micro_jsc | Geom. micro avg. mobility at \(J_{sc}\) | m\(^2\) V\(^{-1}\) s\(^{-1}\) | ||
| \(\mu_{voc}\) | mu_voc | Avg. mobility at \(V_{oc}\) | m\(^2\) V\(^{-1}\) s\(^{-1}\) | ||
| \(\mu^{geom}_{voc}\) | mu_geom_voc | Geom. avg. mobility at \(V_{oc}\) | m\(^2\) V\(^{-1}\) s\(^{-1}\) | \(\sqrt{\langle\mu_e\rangle \langle\mu_h\rangle}\) | |
| \(\mu^{geom\_avg}_{voc}\) | mu_geom_micro_voc | Geom. micro avg. mobility at \(V_{oc}\) | m\(^2\) V\(^{-1}\) s\(^{-1}\) | \(\langle\sqrt{\mu_e \mu_h}\rangle\) | |
| \(\mu^e_{pmax}\) | mu_e_pmax | Avg. electron mobility at \(P_{max}\) | m\(^2\) V\(^{-1}\) s\(^{-1}\) | ||
| \(\mu^h_{pmax}\) | mu_h_pmax | Avg. hole mobility at \(P_{max}\) | m\(^2\) V\(^{-1}\) s\(^{-1}\) | ||
| \(\mu^{geom}_{pmax}\) | mu_geom_pmax | Geom. avg. mobility at \(P_{max}\) | m\(^2\) V\(^{-1}\) s\(^{-1}\) | \(\sqrt{\langle\mu_e\rangle \langle\mu_h\rangle}\) | |
| \(\mu^{geom\_micro}_{pmax}\) | mu_geom_micro_pmax | Geom. micro avg. mobility at \(P_{max}\) | m\(^2\) V\(^{-1}\) s\(^{-1}\) | \(\langle\sqrt{\mu_e \mu_h}\rangle\) | |
| \(\mu_{pmax}\) | mu_pmax | Avg. mobility at \(P_{max}\) | m\(^2\) V\(^{-1}\) s\(^{-1}\) |
| Symbol | JSON token | Meaning | Units | Equ. | Ref |
|---|---|---|---|---|---|
| \(\tau_{voc}\) | tau_voc | Recombination time at \(V_{oc}\) | s | \(R=(n-n_0)/\tau\) | |
| \(\tau_{pmax}\) | tau_pmax | Recombination time at \(P_{max}\) | s | \(R=(n-n_0)/\tau\) | |
| \(\tau^{all}_{voc}\) | tau_all_voc | Recombination time (all carriers) at \(V_{oc}\) | s | \(R=n/\tau\) | |
| \(\tau^{all}_{pmax}\) | tau_all_pmax | Recombination time (all carriers) at \(P_{max}\) | s | \(R=n/\tau\) | |
| \(\theta_{srh}\) | theta_srh | \(\theta_{SRH}\) Collection coefficient at \(P_{max}\) | au | p.100 5.2a |