pvdeg.letid.carrier_factor_wafer#

pvdeg.letid.carrier_factor_wafer(tau, transition, suns, jsc, wafer_thickness, mechanism_params, dn_lit=None)[source]#

Return the delta_n^x_ij term to modify attempt frequency by excess carrier density for a passivated wafer, rather than a solar cell.

For a passivated wafer, delta_n increases linearly with lifetime:

\[\Delta n = \tau*J/W\]

See McPherson 2022 [1]. Requires mechanism_params, a dict of required mechanism parameters. See ‘MECHANISM_PARAMS’ dict

Parameters:

tau (numeric) – Carrier lifetime [us].
transition (str) – Transition in the 3-state defect model (A <-> B <-> C). Must be ‘ab’, ‘bc’, or ‘ba’.
suns (numeric) – Applied injection level of device in terms of “suns”, e.g. 1 for a device held at 1-sun Jsc current injection in the dark, or at open-circuit with 1-sun illumination.
jsc (numeric) – Short-circuit current density [mA/cm^2].
wafer_thickness (numeric) – Wafer thickness [um].
mechanism_params (dict) – Dictionary of mechanism parameters. 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) Parameters are coded in ‘MECHANISM_PARAMS’ dict.
dn_lit (numeric, default None) – Optional, supply in lieu of a complete set of mechanism_params if experimental dn_lit is known.

Returns:

numeric – dn^x_ij term. Modified by the ratio of modeled dn to literature experiment dn (dn/dn_lit).

References

“Excess carrier concentration in silicon devices and wafers: How bulk properties are expected to accelerate light and elevated temperature degradation,” MRS Advances, vol. 7, pp. 438–443, 2022, doi: 10.1557/s43580-022-00222-5.