NexSolveAI Research Toolkit 01 Community Edition v1.3: Research-Quality OSC/PSC/DSSC Structure & Energy Band Diagram Builder

Guided Learning Path

Follow this sequence to move from semiconductor fundamentals to a complete, publication-ready device and energy-level diagram.

Learning Objectives

Introduction

Modern photovoltaic devices are multilayer structures in which light absorption, charge generation, carrier selection, transport, and collection are distributed across different functional materials. The sequence of the substrate, transparent conducting electrode, electron-transport layer, absorber, hole-transport layer, interfacial layers, and counter electrode strongly influences charge extraction and recombination.

This Community Edition provides an interactive environment for constructing and comparing representative perovskite solar cells (PSCs), organic solar cells (OSCs/OPVs), and dye-sensitized solar cells (DSSCs). Users can modify layer order and material parameters, then generate a device-structure illustration and a vacuum-referenced energy-level diagram.

Theory and Scientific Background

1. Vacuum-referenced energy scale

The diagram uses the vacuum level, E_vac = 0 eV, as the common reference. Electron energies in a solid are therefore shown as negative values below vacuum. For a semiconductor with electron affinity χ and bandgap E_g, this toolkit estimates:

Here E_C represents the conduction-band minimum for inorganic semiconductors or an approximate LUMO level for organic materials; E_V represents the valence-band maximum or an approximate HOMO level.

2. Work function and Fermi level

The work function Φ is the energy needed to move an electron from the Fermi level to vacuum. The toolkit therefore places the approximate Fermi level at:

For conductors and electrodes, the displayed horizontal level is based primarily on the work function. Actual values can vary with surface treatment, composition, doping, crystal orientation, contamination, and measurement method.

3. Interfacial band offsets

At an interface between adjacent semiconductor layers 1 and 2, the electron and hole energy discontinuities are represented as:

These offsets help users identify possible extraction barriers and carrier-blocking behavior. A favorable contact should facilitate transport of the desired carrier while suppressing the opposite carrier; however, performance cannot be predicted from offsets alone because defects, dipoles, recombination kinetics, mobility, doping, and morphology are also important.

4. Built-in potential and schematic band bending

When contacts with different work functions form a device, charge redistribution can establish an internal electrostatic potential. The toolkit uses the contact work-function difference as a simple estimate:

Because work functions entered in electron-volts have the same numerical difference as volts per elementary charge, the displayed estimate is numerically the work-function difference in volts. The adjustable band-bending factor applies a schematic linear potential shift across the stack for visualization.

5. Interpretation of the three device families

• PSC: photons generate free or weakly bound carriers in the perovskite absorber; electron- and hole-selective layers direct carriers toward opposite electrodes.
• OSC: excitons generated in donor or acceptor phases reach a donor–acceptor interface, where energetic driving forces and local electric fields support charge-transfer-state formation and separation.
• DSSC: an excited dye injects an electron into the semiconductor conduction band; the oxidized dye is regenerated by the redox mediator, which is then regenerated at the counter electrode.

Representative Materials Database

The values below are the editable starting values used by this Community Edition. They are representative—not universal—and can vary with composition, fabrication, doping, surface treatment, morphology, and measurement method.

Use the Layer Stack Editor to replace these defaults with values appropriate to your own materials and cited experimental conditions.

Interactive Concept Explorer

Select a term to review its role in the diagram and in photovoltaic device operation.

Searchable Glossary

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Electrical Characterization

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Release Notes

Selected References and Further Reading

1. M. A. Green, A. Ho-Baillie, and H. J. Snaith, “The emergence of perovskite solar cells,” Nature Photonics, 8, 506–514 (2014). DOI
2. A. Kojima, K. Teshima, Y. Shirai, and T. Miyasaka, “Organometal halide perovskites as visible-light sensitizers for photovoltaic cells,” Journal of the American Chemical Society, 131, 6050–6051 (2009). DOI
3. B. O’Regan and M. Grätzel, “A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO₂ films,” Nature, 353, 737–740 (1991). DOI
4. C. Deibel and V. Dyakonov, “Polymer–fullerene bulk heterojunction solar cells,” Reports on Progress in Physics, 73, 096401 (2010). DOI
5. B. A. Gregg, “Excitonic solar cells,” Journal of Physical Chemistry B, 107, 4688–4698 (2003). DOI
6. U.S. Department of Energy, “Perovskite Solar Cells” and “Perovskite Research Directions.” DOE overview
7. National Renewable Energy Laboratory, “Organic Photovoltaic Solar Cells.” NREL overview
8. S. M. Sze and K. K. Ng, Physics of Semiconductor Devices, 3rd ed., Wiley (2007), for work functions, energy bands, junction electrostatics, and carrier transport.

References provide foundational background. The material parameters embedded in the toolkit are representative values and are not claimed to reproduce a single measurement condition or publication.

About, License, and Citation

Suggested Citation

Scientific-use notice

The generated band diagrams are schematic, vacuum-referenced design aids. They do not replace experimentally measured energy levels, interface-specific characterization, or full semiconductor/electrochemical device simulation. Cite the source of any parameter values used in scholarly work.