{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "from matplotlib import cm"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from solcore.light_source import LightSource\n",
    "from solcore.solar_cell import SolarCell\n",
    "from solcore.solar_cell_solver import solar_cell_solver\n",
    "from solcore.structure import Junction"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Illumination spectrum"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "wl = np.linspace(300, 4000, 4000) * 1e-9\n",
    "light = LightSource(\n",
    "    source_type=\"standard\", version=\"AM1.5g\", x=wl, output_units=\"photon_flux_per_m\"\n",
    ")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "T = 298\n",
    "V = np.linspace(0, 5, 500)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "This function assembles the solar cell and calculates the IV cruve"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "def solve_MJ(EgBot, EgMid, EgTop):\n",
    "    db_junction0 = Junction(kind=\"DB\", T=T, Eg=EgBot, A=1, R_shunt=np.inf, n=3.5)\n",
    "    db_junction1 = Junction(kind=\"DB\", T=T, Eg=EgMid, A=1, R_shunt=np.inf, n=3.5)\n",
    "    db_junction2 = Junction(kind=\"DB\", T=T, Eg=EgTop, A=1, R_shunt=np.inf, n=3.5)\n",
    "    my_solar_cell = SolarCell(\n",
    "        [db_junction2, db_junction1, db_junction0], T=T, R_series=0\n",
    "    )\n",
    "    solar_cell_solver(\n",
    "        my_solar_cell,\n",
    "        \"iv\",\n",
    "        user_options={\n",
    "            \"T_ambient\": T,\n",
    "            \"db_mode\": \"top_hat\",\n",
    "            \"voltages\": V,\n",
    "            \"light_iv\": True,\n",
    "            \"internal_voltages\": np.linspace(-6, 5, 1100),\n",
    "            \"wavelength\": wl,\n",
    "            \"mpp\": True,\n",
    "            \"light_source\": light,\n",
    "        },\n",
    "    )\n",
    "    return my_solar_cell"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We create an efficiency map using Eg0 as the bandgap of the bottom junction and<br>\n",
    "scanning the bandgaps of the middle and top junctions. Increase N1 and N2 to have<br>\n",
    "higher resolution."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "N1 = 10\n",
    "N2 = 10\n",
    "Eg0 = 1.12"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "all_Eg1 = np.linspace(1.3, 1.8, N1)\n",
    "all_Eg2 = np.linspace(1.7, 2.4, N2)\n",
    "eff = np.zeros((N1, N2))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "N = N1 * N2\n",
    "index = 0\n",
    "Effmax = -1\n",
    "Eg1_max = all_Eg1[0]\n",
    "Eg2_max = all_Eg2[0]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "And we run the calculation"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "for i, Eg1 in enumerate(all_Eg1):\n",
    "    for j, Eg2 in enumerate(all_Eg2):\n",
    "        my_solar_cell = solve_MJ(Eg0, Eg1, Eg2)\n",
    "        mpp = my_solar_cell.iv.Pmpp\n",
    "        eff[i, j] = mpp\n",
    "        if mpp > Effmax:\n",
    "            Effmax = mpp\n",
    "            Eg1_max = Eg1\n",
    "            Eg2_max = Eg2\n",
    "        index += 1\n",
    "        print(int(index / N * 100), \"%\\n\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "optimum_MJ = solve_MJ(Eg0, Eg1_max, Eg2_max)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "plt.figure(1)\n",
    "plt.plot(V, optimum_MJ.iv.IV[1], \"k\", linewidth=4, label=\"Total\")\n",
    "plt.plot(V, -optimum_MJ[0].iv(V), \"r\", label=\"Bottom\")\n",
    "plt.plot(V, -optimum_MJ[1].iv(V), \"g\", label=\"Middle\")\n",
    "plt.plot(V, -optimum_MJ[2].iv(V), \"b\", label=\"Top\")\n",
    "plt.ylim(0, 200)\n",
    "plt.xlim(0, 3.75)\n",
    "plt.legend()\n",
    "plt.xlabel(\"Voltage (V)\")\n",
    "plt.ylabel(\"Current (A/m$^2$)\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "plt.figure(2)\n",
    "eff = eff / light.power_density * 100\n",
    "plt.contourf(all_Eg2, all_Eg1, eff, 50, cmap=cm.jet)\n",
    "plt.xlabel(\"TOP Eg (eV)\")\n",
    "plt.ylabel(\"MID Eg (eV)\")\n",
    "cbar = plt.colorbar()\n",
    "cbar.set_label(\"Efficiency (%)\", rotation=270, labelpad=10)\n",
    "plt.tight_layout()\n",
    "plt.show()"
   ]
  }
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