refactor Sesame PDD into two files, update tests and documentation/do…

…cstrings

docs/source/Solvers/SesameDDsolver.rst

@@ -29,7 +29,7 @@ Sesame:
 - ``electron_minority_lifetime``
 - ``hole_minority_lifetime``
 - ``bulk_recombination_energy``: this is an optional parameter (will be set to 0 by default).
-  It should be set in eV, in the ``Layer`` definition, if the user wants to use a different value
+  It should be set (in joules!), in the ``material`` definition, if the user wants to use a different value
 - ``radiative_recombination``: radiative recombination rate (m\ :sup:`3` s\ :sup:`-1`)
 - ``electron_auger_recombination``: Auger recombination rate for electrons (m\ :sup:`6` s\ :sup:`-1`)
 - ``hole_auger_recombination``: Auger recombination rate for holes (m\ :sup:`6` s\ :sup:`-1`)
@@ -60,6 +60,25 @@ of ``Junction``, or for individual layers by setting the ``doping_profile`` argu
 possible to mix constant doping in some layers with depth-dependent doping in others. The position argument
 of the function should always be in terms of distance from the front surface of the junction or layer it is for.
 
+Outputs
+-------
+In addition to updating the individual junctions and the solar cell as a whole with the current-voltage output
+(if ``solar_cell_solver`` is called with task ``iv``) and quantum efficiency
+(if ``solar_cell_solver`` is called with task ``qe``), the Sesame solver will also update each junction it solves the
+IV for with an attribute called ``pdd_output``, which contains the following:
+
+- ``pdd_output.potential``: the potential (V)
+- ``pdd_output.n``: the electron density (m\ :sup:`-3`)
+- ``pdd_output.p``: the hole density (m\ :sup:`-3`)
+- ``pdd_output.Ec``: the level of the conduction band (eV)
+- ``pdd_output.Ev``: the level of the valence band (eV)
+- ``pdd_output.Efe``: the electron quasi-Fermi level (eV)
+- ``pdd_output.Efh``: the hole quasi-Fermi level (eV)
+- ``pdd_output.Rrad``: the radiative recombination rate (m\ :sup:`-3` s\ :sup:`-1`)
+- ``pdd_output.Raug``: the Auger recombination rate (m\ :sup:`-3` s\ :sup:`-1`)
+- ``pdd_output.Rsrh``: the bulk recombination due to Shockley-Read-Hall processes (m\ :sup:`-3` s\ :sup:`-1`)
+
+Each of these is a 2-dimensional array, with dimensions ``(len(options.internal_voltages), len(mesh))``.
 
 Sub-function documentation
 ---------------------------