Perovskite Film Fabrication: Spin Coating, Antisolvent Timing and Annealing

Perovskite films begin to crystallise during the few seconds of spinning, so how and when nucleation is triggered strongly influences film quality. This guide explains the one-step and two-step routes, the antisolvent step and its timing, how to write the spin program, why atmosphere and substrate temperature matter, how annealing shapes the film, and where to go when a process outgrows spin coating.

In one paragraph: Perovskite films crystallise rather than simply dry, so nucleation control is a central part of the process [4][5]. An antisolvent applied to the spinning wet film can influence nucleation and morphology; its timing and application rate matter [4][5][7]. Record the drip timing relative to the spin program, control the atmosphere, and treat substrate temperature as a recipe parameter [11][12][14]. Annealing temperature, time and atmosphere shape morphology, coverage and stability [15][16][17].

1.  Why Spin Coating for Perovskite Films

Metal halide perovskites entered photovoltaics in 2009, when Kojima and co-workers used organometal halide perovskites as visible-light sensitizers in photoelectrochemical cells [1]. Since then, most laboratory perovskite films have been made from solution, and spin coating is the method most labs start with: it needs a few drops of precursor solution, gives a film in under a minute, and the same program can be repeated on every substrate.

Spin coating a perovskite is not the same as spin coating a polymer, though. The film does not simply dry; it crystallises. The precursor solution contains lead halide and organic or inorganic cation salts dissolved in polar solvents, and the species in solution, including complexes with the solvent, affect the film that forms [3]. When and how fast crystals nucleate during the few seconds of spinning strongly influences whether the film is dense and continuous or rough and full of gaps [4][5][16].

This guide covers the process steps a lab controls: the deposition route, the antisolvent step and its timing, the spin program, the atmosphere, substrate temperature, and the anneal. It closes with troubleshooting and the route to larger areas. It describes general process logic from the cited literature; it does not give a recipe for a specific composition, and it makes no claims about device efficiency. General spin coating background is in Spin Coating Explained: Stages, Physics and Film Thickness.

2.  One-Step and Two-Step Routes

Two families of solution routes are common in the literature:

Simplified overview; many variants exist, including vapour-assisted conversion and additive approaches.

In the sequential route described by Burschka and co-workers, lead iodide was deposited from solution into a nanoporous titanium dioxide film and then transformed into the perovskite by exposure to a solution of methylammonium iodide [2]. The one-step route combines everything in one solution and relies on controlling crystallisation during spinning. Compositional work, such as mixing formamidinium lead iodide with methylammonium lead bromide, has used the one-step route with an antisolvent step [8].

Either way, the precursor solution is a starting point that deserves attention: interactions between the precursors and coordinating solvent molecules lead to intermediate species and phases that affect how uniform and dense the film becomes [3]. Make solutions the same way every time and record how old they are when coated.

3.  The Antisolvent Step and Its Timing

Antisolvent treatment is widely used in perovskite spin coating. During spinning, a second solvent that is compatible with the host-solvent system but reduces precursor solubility is applied to the wet film. Depending on the precursor chemistry, solvent interactions and application conditions, this can promote nucleation and influence the resulting film morphology [4][5][7].

• Solvent engineering. Jeon and co-workers used a mixed solvent containing DMSO and dripped toluene during spinning. They reported that an intermediate phase formed with the solvent and converted to a uniform, dense perovskite film on annealing [4].
• Fast deposition–crystallisation. Xiao and co-workers spin coated a DMF solution and exposed the wet film to a second solvent, such as chlorobenzene, immediately after deposition to induce crystallisation, giving flat, uniform films [5].
• Antisolvent choice and morphology. Paek and co-workers studied how the antisolvent treatment shapes the morphology of perovskite films from the nanometre to the micrometre scale [6].
• Application rate. Taylor and co-workers compared 14 antisolvents in nearly 800 devices and reported that the rate at which the antisolvent is applied, matched to the properties of the antisolvent, is a key variable for obtaining good films [7].

Timing: when the drip lands

The common thread is timing. Reported drip delays and antisolvent volumes vary widely between published studies [7], so there is no universal drip time. The right moment depends on the solution, the antisolvent, the spin speed, the volume and the room conditions, so labs determine it experimentally and then keep everything else constant [4][5][7].

What makes antisolvent work reproducible is to treat the drip as a defined, recorded part of the recipe:

• define the drip time relative to a stated point in the spin program, such as the start of a step, and record it;
• keep the antisolvent volume and application rate constant [7], and record the pipette or nozzle height;
• dispense onto the centre of the rotating substrate;
• keep the time between antisolvent drip and annealing constant.

Dispensing technique in general, from static and dynamic dispense to nozzle height, is covered in Static vs Dynamic Dispense in Spin Coating: Volume, Coverage and Material Waste.

4.  Writing the Spin Program

The film thickness of a spin-coated layer follows the same physics as any other solution: once the film has set, thickness falls approximately with the reciprocal square root of the spin speed [9][10], and in Meyerhofer’s model it increases with the initial viscosity of the solution [9]. A spin curve for your solution therefore remains the best way to hit a target thickness; see Spin Coating Explained: Stages, Physics and Film Thickness for the physics and the stages of spinning.

Perovskite programs are typically written in two or more steps, with the antisolvent drip placed inside one of them. Instead of copying numbers from a paper, define each step by what it has to do:

Template for documenting a program; values depend on the composition and solvent system and are found experimentally.

Ramps matter as well. A fast ramp reaches the final speed before much solvent has evaporated, while a slow ramp lets the film start to dry at lower speed; how acceleration changes thickness and uniformity is covered in Spin Coating Acceleration and Multi-Step Recipes: What the Ramp Actually Does. Defects that come from the coater rather than the chemistry, such as comets, streaks and edge beads, are treated in Spin Coating Defects: Comets, Striations, Pinholes and Edge Beads Diagnosed.

Because the drip is timed relative to the spin program, record its intended time and the method used to deliver it. Fine step-time resolution and multi-step recipe storage can help document the sequence, but do not by themselves establish automated dispensing or synchronisation between a dispenser and the spin program.

5.  Atmosphere: Oxygen, Moisture and the Glovebox

Many perovskite compositions react with their environment. Aristidou and co-workers studied the role of oxygen in the degradation of methylammonium lead iodide films under light [11]. Leguy and co-workers showed that methylammonium lead iodide hydrates reversibly in humid air in films, crystals and devices [12]. Moisture is not only harmful, however: You and co-workers reported that annealing the precursor film in a humid environment, such as ambient air, improved film quality and grain size in their process [13].

The practical conclusion is that atmosphere is a process variable to control and record, whatever the target:

• Glovebox processing. Coating and annealing in a nitrogen glovebox removes most of the variation from room humidity. Spin coaters and hot plates designed to fit into a glovebox make this practical.
• Ambient processing. If films are made in air, record relative humidity and temperature for every run, and expect results to drift with the weather.
• Solvent vapour. Repeated coating can introduce solvent vapour into a glovebox and affect evaporation or atmosphere management. Assess solvent loading, exhaust and purification requirements, and follow the glovebox manufacturer’s and laboratory’s approved operating procedure rather than assuming that routine purging alone will stabilise the process.

Annealing under nitrogen outside a glovebox, and what an inert hot plate can and cannot do, is covered in Annealing Under Nitrogen: Inert Hot Plates for Air-Sensitive Films.

6.  Substrate Temperature and Hot Casting

Substrate and solution temperature are further levers. Nie and co-workers reported a hot-casting technique in which a hot precursor solution is spin coated onto a hot substrate, producing perovskite films with millimetre-scale grains [14]. Even without going that far, the substrate temperature changes how fast solvent evaporates during spinning and therefore when crystallisation starts.

A heated spin coater allows the spin-table temperature to be controlled during the run. The actual substrate and wet-film temperatures may differ from the setpoint, so qualify the thermal conditions for the intended process. How temperature changes evaporation, viscosity and thickness, and the limits of heated spin tables, are covered in Heated Spin Coating: How Substrate Temperature Changes Evaporation and Thickness.

7.  Annealing: Temperature, Coverage and Stability

Almost every solution-processed perovskite film is annealed on a hot plate after spinning to complete crystallisation and remove residual solvent. The anneal also shapes the film:

• Temperature and morphology. Dualeh and co-workers showed that the annealing temperature affects the film morphology of a solution-processed perovskite and, with it, device behaviour [15].
• Coverage. Eperon and co-workers showed for planar films that surface coverage depends on processing conditions including the annealing temperature, the film thickness and the atmosphere, and that incomplete coverage limits device performance [16].
• Thermal stability. Conings and co-workers reported that methylammonium lead iodide degrades on heating even in an inert atmosphere, an intrinsic thermal instability rather than only an effect of air or moisture [17].

Together, these results argue for a precise, well-documented anneal: a hot plate whose temperature is accurate and uniform across the substrate, a fixed time, a fixed time between spinning and annealing, and a defined atmosphere. What soft bake, post-bake and anneal steps do in general is explained in Soft Bake, Post-Bake and Annealing on a Hot Plate: What Each Step Does; annealing under nitrogen is covered in Annealing Under Nitrogen: Inert Hot Plates for Air-Sensitive Films.

8.  Troubleshooting Perovskite Films

Starting points summarised from the cited literature and general spin coating practice; the right fix depends on the composition.

Coating-side defects in more depth are in Spin Coating Defects: Comets, Striations, Pinholes and Edge Beads Diagnosed. Choosing a spin coater for this kind of work, from substrate size to glovebox fit, is covered in How to Choose a Lab Spin Coater: Speed, Acceleration, Substrate Size and Glovebox Fit.

9.  Beyond Spin Coating and Further Reading

Spin coating is widely used at laboratory scale, while larger-area processes can use other deposition methods. Deng and co-workers demonstrated perovskite active layers made by doctor-blade coating [18]. Gas quenching is another approach used to control solvent extraction and crystallisation in solution-processed perovskite films, including films made by blade coating [19]. Its suitability depends on the coating method and formulation. What changes when a recipe moves from spin coating to blade or slot-die coating is the topic of From Spin Coating to Slot-Die and Blade: Scaling a Thin-Film Ink; gas quenching is covered in Air-Knife and Gas Quenching for Blade- and Slot-Die-Coated Films.

Perovskite case studies on this blog

Several earlier articles on this blog summarise published perovskite work in which graphene materials were used in the device stack:

• Graphene Dispersion Passivation for Perovskite Cells - UKM, 2021
• Reduced Graphene Oxide HTM for Perovskite Solar Cells - University of Padova, 2018
• Single-Layer Graphene in 2D Perovskite Solar Cells - LBNL, 2020
• Single Layer Graphene for Perovskite-Silicon Tandems - Zhejiang University, 2021

10.  Levon™ Spin Coaters and Hot Plates for Perovskite Films

The tables quote the Levon™ product pages; “Not stated” means the page does not give the value. The EZ4-S, IC5000-S and AC200 pages list perovskite solar-cell and organic optoelectronic semiconductor research among their application areas. These application listings do not establish a validated recipe or a particular film outcome.

Specifications as published on the Levon™ product pages on 22 October 2026, where “no load” is stated by the page. The supplied configuration is confirmed in the quotation.

Specifications as published on the Levon™ product pages on 22 October 2026. The HP100-SA page does not state a residual oxygen or moisture level; a hot plate with nitrogen input is not a substitute for a glovebox. The supplied configuration is confirmed in the quotation.

How this connects to the guide: the EZ4-S has a glovebox-compatible design for round substrates up to the 4-inch maximum recommended diameter, relevant to the glovebox processing of Section 5. The AC200 series can be recessed into a glovebox and runs 100 recipes of up to 100 steps at 0.1 s step-time resolution on the S-PP, SE and PE models, which can help document the step during which an antisolvent drip is made (Section 4). The IC5000-S heats the spin table from room temperature to 150 °C for the substrate-temperature work of Section 6. For annealing (Section 7), the HP6 has a recessed design for glovebox integration and reaches 250 °C with ±0.2 °C control precision after stabilisation; the HP100-SA has a nitrogen input and a height-reducible, flush-mount design. Questions about a specific configuration can be sent through the contact form.

11.  Keep Exploring the Perovskite and Thin-Film Knowledge Hub

Start here

• Spin Coating Explained: Stages, Physics and Film Thickness — stages and physics of spin coating
• Spin Coating Acceleration and Multi-Step Recipes: What the Ramp Actually Does — acceleration and multi-step recipes
• Heated Spin Coating: How Substrate Temperature Changes Evaporation and Thickness — heated spin coating and substrate temperature
• How to Choose a Lab Spin Coater: Speed, Acceleration, Substrate Size and Glovebox Fit — choosing a spin coater

Process steps

• Soft Bake, Post-Bake and Annealing on a Hot Plate: What Each Step Does — soft bake, post-bake and annealing
• Annealing Under Nitrogen: Inert Hot Plates for Air-Sensitive Films — annealing under nitrogen
• From Spin Coating to Slot-Die and Blade: Scaling a Thin-Film Ink — scaling an ink from spin to blade and slot-die
• Air-Knife and Gas Quenching for Blade- and Slot-Die-Coated Films — gas quenching for blade- and slot-die-coated films

Links will be added as each article is published.

Equipment

• EZ4-S Spin Coater — compact, glovebox-compatible, up to 4-inch round
• AC200 Spin Coater Series — recessable into a glovebox, 100 recipes
• IC5000-S Heated Spin Coater — spin table RT to 150 °C
• HP6 Hot Plate — RT to 250 °C, glovebox integration
• HP100-SA Hot Plate — nitrogen input, RT to 300 °C
• Levon™ Spin Coaters — all spin coaters

Questions about a specific instrument can be sent through the contact form.

12.  FAQ

13.  References