Overview

PVSim (Semiconductor Physics Analysis and Research Code) is an open-source 1D/2D drift-diffusion TCAD simulation platform for solar cells. It includes automatic Bayesian parameter optimization and a local LLM assistant, operating completely locally without requiring external API keys.

Installation

You can install the base package via pip:

pip install pvsim-pv

For a full research stack including NIST Sesame solver and BoTorch optimization, run:

pip install "pvsim-pv[tcad,botorch]"

pip install git+https://github.com/usnistgov/sesame.git

Note: The NIST Sesame TCAD solver is not published on PyPI, so installing it separately via Git is required.

Extras Packages

Extra	Contents
tcad	Numba (JIT compilation for Sesame)
botorch	PyTorch CPU + BoTorch (advanced Gaussian Process optimization)
workers	Celery + Redis (distributed asynchronous simulations)
llm-local	Ollama (local LLM assistant, zero API keys required)
llm-cloud	Anthropic / OpenAI / Mistral / Gemini Integration
materials	mp-api + pymatgen (online Materials Project fetching)
all	Installs all of the above extras

CLI Commands

pvsim-web # Starts Flask Web Server → http://localhost:5000

pvsim-tui # Interactive Rich TUI (CLI) with 17 screens

pvsim run config.json # Run batch simulations from JSON files

pvsim-config # Setup assistant to generate local .env

JSON Configuration Format

{
  "simulation_name": "si_homo_baseline",
  "simulation_type": "homojunction",
  "materials": { "active": "Si" },
  "geometry": {
    "thickness_n": 5e-5,
    "thickness_p": 2e-4,
    "nx": 100
  },
  "doping": {
    "n_region": 1e17,
    "p_region": 1e15
  },
  "voltages": { "start": 0.0, "stop": 0.7, "points": 50 },
  "illumination": {
    "enabled": true,
    "photon_flux": 2.5e17,
    "absorption_coefficient": 1e4
  }
}

Simulation Capabilities

27 Simulation Routes

Simple Junctions (homojunction, heterojunction, graded)
Multi-layers (up to 7 layers) & Multijunctions (tandem, triple)
Defect systems (continuous defects, grain boundaries)
Parametric sweep, temperature, and light studies
QE, CV, EBIC, and Transient Photovoltage characterization

15 Validated Materials

Pre-configured with physical properties (Nc, Nv, mobility, lifetime, Auger/radiative rates):

SiGeGaAsGaPInPCdTeCdSCIGSCZTSMAPbI3CsPbI3FAPbI3GaInPAlGaAsGaN