Flexible Solar Cell Coating Solution

Commonly Used PVD Deposition Electrode Materials:

• Transparent Conductive Oxides (TCO): ITO (Indium Tin Oxide), AZO (Aluminum-doped Zinc Oxide), GZO (Gallium-doped Zinc Oxide), etc., used for front electrodes.

• Ultrathin Metal Electrodes: Ag, Cu, Au nanowires or grids (thickness < 100nm), balancing conductivity and transparency.

• Composite Electrodes: Metal/oxide stacks (e.g., Ag/ZnO), optimizing optical/electrical properties through multi-layer PVD deposition.

(1) Transparent Conductive Electrode (TCO) Preparation

• Magnetron Sputtering (MS-PVD) for ITO Deposition:

  ITO is sputtered on flexible substrates (PET, PI) at low temperatures (<150°C). The resistivity can be as low as 10⁻⁴ Ω·cm, with transmittance >90% at 550nm.

  Challenge: Indium is a scarce resource, requiring the development of alternative materials such as AZO and GZO. Carrier concentration is controlled through reactive sputtering (introducing O₂).

• Ultrathin Metal Electrodes:

  Thermal Evaporation is used to deposit 5-10nm ultrathin Ag, combined with an anti-reflection layer (e.g., MoO₃) to achieve a transmittance >85% and sheet resistance <10 Ω/sq.

  Application Example: In perovskite solar cells, Ag/ITO composite electrodes improve device efficiency to >25%.

(2) Back Electrodes and Metal Grids

• Mo Back Electrode for Flexible CIGS Solar Cells:

  Mo is sputtered on polyimide (PI) at a thickness of approximately 500nm. Stress must be controlled to prevent substrate warping.

  Optimization: Gradient deposition (low power → high power) improves adhesion, with no cracks after bending tests.

• Metal Nanowire Grid:

  Ag/Cu is sputtered or evaporated using a mask to form micron-sized grids, filled with transparent conductive polymers (e.g., PEDOT:PSS), achieving sheet resistance <5 Ω/sq and transmittance >90%.