mzszym/oedes

Organic Electronic Device Simulator

oedes - organic electronic device simulator

This is work in progress. See doc/ for documentation, and examples/ for examples of use.

Installation

pip install oedes

It is recommended to run test suite after installing

python -c "import oedes; oedes.test()"

Example simulation

This builds and solves a model of abrupt PN junction:

import oedes
from oedes import models

# Define doping profile
def doping_profile(mesh, ctx, eq):
    Nd = ctx.param(eq, 'Nd')
    Na = ctx.param(eq,'Na')
    return oedes.ad.where(mesh.x<mesh.length*0.5,Nd,-Na)

# Define device model
poisson = models.PoissonEquation()
temperature = models.ConstTemperature()
electron = models.BandTransport(poisson=poisson, name='electron', z=-1, thermal=temperature)
hole = models.BandTransport(poisson=poisson, name='hole', z=1, thermal=temperature)
doping = models.FixedCharge(poisson, density=doping_profile)
semiconductor = models.Electroneutrality([electron, hole, doping],name='semiconductor')
recombination = models.DirectRecombination(semiconductor)
anode = models.OhmicContact(poisson, semiconductor, 'electrode0')
cathode = models.OhmicContact(poisson, semiconductor, 'electrode1')
equations=[ poisson, temperature, electron, hole, 
            doping, semiconductor, anode, cathode,
            recombination ]

# Define device parameters
params={
    'T':300,
    'epsilon_r':12,
    'Na':1e24,
    'Nd':1e24,
    'hole.mu':1,
    'electron.mu':1,
    'hole.energy':-1.1,
    'electron.energy':0,
    'electrode0.voltage':0,
    'electrode1.voltage':0,
    'hole.N0':1e27,
    'electron.N0':1e27,
    'beta':1e-9
}

# Discretize and solve discrete model
mesh = oedes.fvm.mesh1d(100e-9)
model = oedes.fvm.discretize(equations, mesh)
c=oedes.context(model)
c.solve(params)

# Plot bands and quasi Fermi potentials
import matplotlib.pylab as plt
p=c.mpl(plt.gcf(), plt.gca())
p.plot(['electron.Eband'],label='$E_c$')
p.plot(['hole.Eband'],label='$E_v$')
p.plot(['electron.Ef'],linestyle='--',label='$E_{Fn}$')
p.plot(['hole.Ef'],linestyle='-.',label='$E_{Fp}$')
p.apply_settings({'xunit':'n','xlabel':'nm'})
p.ax.legend(loc=0,frameon=False)
plt.show()

oedes's Issues

Physical quantities behind absorption() and 'generation.I'

Hallo!

In the photovoltaics steady-state example, to which physical quantities do 'absorption()' and 'generation.I' (part of the loaded standard parameters) prrecisely refere to?
Could it be the number of absorbed photons per volume element and time, and internal quantum efficiency, respectively?

Thanks a lot!

Bilayer photovoltaics

Hello!
I would like to use oedes for the simulation of organic bilayer photovoltaic cells in the steady state. Does oedes already offer a model dedicated to this scenario? If not, which moduls of the software would I have to adopt for such simulations?

In some more detail:
Starting from the (effectively homogeneous) bulkheterojunction PV cell with its boundary conditions as included e.g. in the oedes examples, I would like to "spacially" seperatethe sets of transport equations for electrons and holes into two distinct half spaces (incl. different band gaps / absorption coefficients). As it shouldn’t make a difference in the steady state, I would be pleased incorporating generation and recombination of charge carriers at the domain interface either

• by some “charge source” terms $(\partial n/\partial t)_{gen./recomb.} = …$ (same for holes) within a finite width $h$ around the interface and $n = p = 0$ at the interface (las done e.g. by Barker et al., Phys. Rev. B 67:075205 (2003), https://link.aps.org/doi/10.1103/PhysRevB.67.075205),

• or by formulating it in terms of boundary conditions for the charge carrier fluxes (as done e.g. by Trukhanov et al., Phys. Rev. B 84:205318 (2011), https://link.aps.org/doi/10.1103/PhysRevB.84.205318).

Thank you very much in advance!