Perovskite Solar Cell Fabrication

Updated 5 November 2025

Perovskite solar cell fabrication is the process of forming polycrystalline thin films using solution, vapor, and hybrid deposition methods to optimize morphology and stability.
Critical parameters such as solvent evaporation rate, crystallization kinetics, and precursor chemistry are finely tuned to produce flat, pinhole-free films with high device efficiency.
Innovative scalable techniques like hybrid PVD/blade coating and flexographic printing enhance industrial compatibility while improving performance and long-term stability.

Perovskite solar cell fabrication encompasses diverse methodologies ranging from solution-processable approaches to vapor-phase and hybrid deposition routes. At the core of all methods is the precise construction of a polycrystalline thin film based on the general formula ABX₃ (e.g., CH₃NH₃PbI₃), in which the choice of precursor chemistry, process parameters, and environmental control fundamentally impact film morphology, device performance, and operational stability.

1. Principle Approaches to Perovskite Thin Film Formation

Perovskite absorber layers are fabricated by solution-processing (e.g., spin-coating, blade coating, inkjet), vapor-phase deposition (e.g., co-evaporation, chemical vapor deposition), or hybrid strategies combining vapor and solution steps. Solution-processed films rely on anti-solvent engineering, ink formulation, and controlled crystallization kinetics, while vapor-phase approaches (co-evaporation or CVD) prioritize morphological uniformity, stoichiometry control, and substrate compatibility.

Co-evaporation: Simultaneous physical vapor deposition of PbI₂ and organic halide (e.g., CH₃NH₃I), often under high vacuum, yields stoichiometric films with optimal crystallinity but extreme sensitivity to environmental exposure (Wang et al., 2015).
Spin-coating with antisolvent: Controlled addition of an orthogonal antisolvent during spin-coating enables rapid supersaturation and crystallization. The universality of this method is established by tuning the antisolvent application rate to its solubility and miscibility characteristics (Taylor et al., 2021).
Hybrid PVD/blade coating: Sequential PVD of inorganic halide (e.g., CsI, PbI₂) followed by blade coating of organic precursors in green solvents (e.g., isopropanol) combines the uniformity of vapor templates with scalable, additive-friendly solution steps (Siegrist et al., 2021).
Chemical vapor reaction: Exposing PLD-deposited PbI₂ films to MAI vapor at high temperature allows for controllable grain growth and exceptional phase purity (Zhang et al., 2017).
Green solvent and phase-engineered sequential deposition: The use of renewable, high-volatility solvents with sequential 2D/3D phase transformation in air eliminates residual toxic solvents and enhances α-FAPbI₃ stability (Gallant et al., 12 Jun 2024).
Back-contact and layer-free architectures: Charge extraction can be achieved solely using SAM-induced dipole fields at metal-perovskite interfaces, bypassing traditional CTLs (Lin et al., 2017).

2. Critical Parameters in Morphology and Crystallization

The film morphology, specifically flatness, pinhole density, and grain structure, is dictated by a balance between solvent evaporation rate ( $v_e$ ), crystal growth rate ( $v_g$ ), and nucleation density. The interplay of these factors determines the formation pathway and final morphology:

High $v_e/v_g$ ratio or high nucleation density (low $L/h_0$ ) produces flat, pinhole-free films. This is exploited in vacuum flash, gas quenching, or anti-solvent accelerated drying (Majewski et al., 4 Sep 2025).
Low $v_e/v_g$ and sparse nucleation results in rough, pinhole-rich morphologies detrimental to device efficiency.
The solution model defines clear process windows: either increase $v_e/v_g$ (quicker evaporation) or seed high nucleation density to avoid pinholes and incomplete coverage.

Table: Morphology Control in Solution-Processed Films | $v_e/v_g$ | Nucleation Density ( $L/h_0$ ) | Morphology | |:---------:|:----------------------------:|:------------------| | High | Any | Flat, pinhole-free| | Moderate | High | Rough, pinhole-free| | Low | Low | Pinhole-rich |

3. Device Stack Engineering and Interface Optimization

Device stacks typically adopt either planar (n-i-p or p-i-n) or mesostructured architectures. Material selection and layer engineering critically influence performance:

Electron Transport Layers (ETL): Compact TiO₂ deposited via pulsed laser deposition ensures pinhole-free, ultrathin layers with superior performance to spin-coated analogs (Zhang et al., 2018). SnO₂ and low-temperature NiO are employed for scalable, flexible, and stable devices (Huddy et al., 2022, Jagadamma et al., 2019).
Hole Transport Layers (HTL): Double-HTLs (CuO and I₂O₅-doped Spiro-OMeTAD) with engineered valence band offsets enhance interfacial energy alignment, reducing recombination and boosting carrier selectivity (Rahman et al., 3 Sep 2025). Inverted architectures employ NiO or co-doped spinel nickel cobaltite, which, when appropriately engineered, maximize conductivity and ionization potential for improved charge extraction (Ioakeimidis et al., 2019, Jagadamma et al., 2019).
SAMs and Compositional Passivation: Self-assembled monolayers (Me-4PACz, DAP) enable both energy alignment and defect passivation. DAP forms larger cations at the perovskite/ETL interface for enhanced $V_\mathrm{OC}$ and FF, while Me-4PACz's integration requires tailored solvent systems for effective ink-substrate interaction (Taddei et al., 27 Nov 2024, Kulkarni et al., 2023).

4. Environmental and Chemical Control during Processing

Ambient processing is enabled by identifying absolute water vapor pressure (WVP) as the universal parameter controlling film quality, in contrast to relative humidity (RH). A WVP < $1.6~\mathrm{kPa}$ is necessary for high efficiency and reproducibility regardless of RH or temperature. Precursor solution composition (especially DMSO:Pb $^{2+}$ ratio) must be dynamically optimized as a function of WVP (Contreras-Bernal et al., 2019). Processing with green solvents (e.g., MeTHF/BA in sequential 2D/3D conversion (Gallant et al., 12 Jun 2024), isopropanol/DMF/DMSO/NMP blends (Kulkarni et al., 2023)) mitigates toxicity and supports industrial scale-up.

5. Innovations in Scalable Processing and Industrial Compatibility

Emerging techniques address manufacturing bottlenecks:

Flexographic printing of NiO $_x$ : Achieves deposition speeds up to $60~\mathrm{m/min}$ , film thicknesses as low as 5 nm, and extremely low pinhole density, outperforming spin-coated controls, and compatible with rapid annealing ( $1~\mathrm{min}$ ) (Huddy et al., 2022).
Hybrid PVD/blade coating: Enables full stack construction in ambient air, incorporating passivation and additive strategies efficiently over $5\times5~\mathrm{cm}^2$ substrates with high device uniformity (Siegrist et al., 2021).
All-vapor-phase and CVD routes: One-step co-evaporation and CVD of perovskite precursors deliver highly ordered, pinhole-free films and compatibility with texturized Si for tandems (Zhang et al., 17 Apr 2024, Muratov et al., 2023).

6. Stability Considerations and Degradation Pathways

Materials stability remains the central challenge for perovskite solar cells. For organo-lead halide absorbers (CH₃NH₃PbI₃), exposure to air (humidity) induces rapid decomposition to PbI₂ within ~22 hours, accompanied by complete N loss, severe I deficiency, roughening, voids, and exposure of the contact layer, as established by XRD, XPS, and AFM studies (Wang et al., 2015). Degradation mechanisms, such as moisture-catalyzed hydrolysis (yielding volatile NH₃, HI), cannot be suppressed by ultrathin PbI₂ capping layers. Robust encapsulation and architectural engineering to prevent air/moisture ingress are mandatory.

Stability improvements are realized via:

Green solvent sequential deposition and 2D/3D phase engineering: Achieves ISOS-L-2 (thermal/light) and ISOS-D-3 (damp heat) stabilities far exceeding multi-cation alloyed benchmarks (Gallant et al., 12 Jun 2024).
Double-HTL band and nanophotonic engineering: Hierarchical morphologies maintain >94% PCE at elevated temperatures (52°C), and reduce thermal/photonic losses (Rahman et al., 3 Sep 2025).

7. Device Performance Metrics and Efficiency Maximization

Optimized fabrication routes yield record PCEs:

Universal antisolvent approach: PCE $>21\%$ for a wide range of antisolvents and up to 6% precursor stoichiometry mismatch (Taylor et al., 2021).
Blade-coated and green-processed triple-cation devices: PCE up to 18.7% with high area uniformity and scalability (Siegrist et al., 2021).
Double-HTL/ellipsoidal nanostructured devices (simulated): PCE up to 26.38%, J $_{sc}$ 29.29 mA/cm $^2$ , thermal durability (Rahman et al., 3 Sep 2025).
DAP-passivated Si-perovskite tandems: PCE up to 25.29%, FF exceeding 75%, and V $_{\mathrm{OC}}$ above 1.9 V (Taddei et al., 27 Nov 2024).

Stack and parameter optimization, passivation of trap states, precise interface control, and suppression of residual solvent content are recurring themes in high-efficiency, stable perovskite solar cell fabrication.

In summary, progress in perovskite solar cell fabrication is driven by a refined understanding of crystallization dynamics, solvent systems, interface energetics, environmental controls, and scalable process integration. The synthesis of these dimensions enables the realization of devices that combine high efficiency, scalability, reproducibility, and operational durability—addressing both fundamental scientific and practical engineering requirements in next-generation photovoltaics.