Charge transfer in UC module

[rwmacq]

From my modelling, I think it's necessary to add charge transfer to the current exciton-only UC model. Triplet generation by charge transfer would function as follows:

• holes transfer from the perovskite to the rubrene layer based on the valance band/HOMO offset (an input parameter), obeying charge conservation and so on.
• electrons transfer from the perovskite to the rubrene layer at a rate dependent on the hole concentration in the adjacent rubrene layer
• for simplicity, we could assume holes do not migrate far into the rubrene layer, but stay trapped in the first bin (i.e. in the vicinity of the interface). I think charge balance would make this the case even if hole diffusion throughout the film was enabled.
• It would be valuable to be able to run sims with both triplet generation models and compare the results side by side. Therefore, having the charge-transfer UC process running in a different module might be a good idea. Alternatively, a flag to decide the triplet generation mechanism could also work well.

[eistrup]

TripletGeneration_rate = n_mapic_interface h_rubrene_interface SequentialChargeTransfer_rate