pvdeg.letid.calc_letid_lab

pvdeg.letid.calc_letid_lab(tau_0, tau_deg, wafer_thickness, s_rear, na_0, nb_0, nc_0, injection, temperature, mechanism_params, duration='3W', freq='min', start=None, generation_df=None, d_base=27, cell_area=239)

Models LETID progression in a constant temperature and injection (i.e. lab-based accelerated test) environment.

Parameters:

• tau_0 (numeric) – Initial bulk lifetime [us]

• tau_deg (numeric) – Fully degraded bulk lifetime [us]

• wafer_thickness (numeric) – Wafer thickness [um]

• s_rear (numeric) – Rear surface recombination velocity [cm/s]

• na_0 (numeric) – Initial percentage of defects in state A [%]

• nb_0 (numeric) – Initial percentage of defects in state B [%]

• nc_0 (numeric) – Initial percentage of defects in state C [%]

• injection (float) – Injection of device. Normalized to 1-sun illumnation or short circuit current. Typical injection in standard accelerated testing is 2x(Isc-Imp), i.e., roughly 0.1. TODO: accept timeseries of injection for modeling variable-condition testing.

• temperature (numeric) –

  Test temperature of device [C]. IEC TS 63342 specifies 75C.

  mechanism_paramsstr

  Name for mechanism parameters set. Parameters are coded in ‘kinetic_parameters.json’. These are typically taken from literature studies of transtions in the 3-state model. They allow for calculation the excess carrier density of literature experiments (dn_lit)

• duration (str, default "3W") – Duration of modeled test. Generates a timeseries using pandas.to_timedelta. Default is 3 weeks, i.e. the length of IEC TS 63342.

• freq (str, default "min") – See pandas.date_range for details. In general, choose short time intervals unless you’re sure defect reactions are proceeding very slowly.

• start (str or datetime-like or None, default None) – If provided, defines the start time of the test. If none, defaults to now.

• generation_df (pandas DataFrame or None) – Dataframe of an optical generation profile for a solar cell used to calculate current collection. If None, loads default generation profile from ‘PVL_GenProfile.xlsx’. If not None, column names must include: - 'Generation (cm-3s-1)' - 'Depth (um)' TODO: improve this.

• d_base (numeric, default 27) – Minority carrier diffusivity of the base of the solar cell [cm^2/Vs].

• cell_area (numeric, default 239) – Cell area [cm^2]. 239 cm^2 is roughly the area of a 156x156mm pseudosquare “M0” wafer

Returns:

timesteps (pandas DataFrame) – Datafame containing defect state percentages, lifetime, and device electrical parameters