Perovskite Solar Cell Processing

The first solar panels were based on silicon wafers, and c-Si, or crystalline silicon, continues to be the dominant material used in photovoltaics. But ever since the first solar panels were deployed, there has been a continuous quest for higher efficiency and lower cost panels. A second-generation material, CdTe, or cadmium telluride, is a thin-film semiconductor that has begun to achieve commercial success. Although not as efficient as silicon, CdTe is lower cost.

A third-generation material, Perovskite, could be a game-changer. It has the potential for both higher efficiency and lower cost compared to c-Si and CdTe. However, Perovskite is still laboratory-based and has not yet reached commercial viability. Nevertheless, the growth rate of Perovskite's demonstrated efficiency has been faster than that of silicon and CdTe.

Lasers Will Help Enable Commercial Viability of Perovskite Solar Cells

Perovskite solar cell manufacturing is a roll-to-roll process. Part of the process involves removing very narrow portions of thin-film layers of material in a multi-film stack without delamination or debris. This is commonly referred to as "patterning" or "scribing," which is done to achieve monolithic serial interconnections with adjacent cells. Traditional mechanical scribing methods, such as with a blade, and wet chemical etching methods have limitations and may cause undesired problems. Thankfully, a superior solution for Perovskite solar cell manufacturing is available: lasers. Here are some of the reasons why.

  • Lasers are very high precision devices that can perform accurately and repeatability on the order of microns. This helps increase manufacturing yields. By contrast, traditional mechanical tools cannot reliably perform on nearly the same scale. In addition to their high precision, lasers offer more variable and intricate patterns for scribing compared to mechanical tools, which may enable more complex, and possibly more efficient, Perovskite solar cell designs.
  • Lasers deliver higher quality results by producing fewer burrs than mechanical scribes and cuts do with less thermal damage to the surrounding areas. This further results in higher manufacturing yields, as less of the material is wasted. Additionally, this can also lead to better quality and reliability of the product in the field, as fewer of these issues will end up in the final assembly.
  • Laser scribing is a contact-free operation with no tool wear. Thus, replacement downtime is exceedingly infrequent by comparison to mechanical methods.
  • Lasers are a more "green" technology. By contrast, a particular concern of wet chemical etching is that the waste management required presents extra complications and costs. Lasers, however, do not produce environmental waste.

Taken all together, MKS believes that incorporating lasers into Perovskite solar cell manufacturing will help to accelerate their commercial viability.

Figure 1. Schematic of laser-based Perovskite cell patterning and selective layer material removal to construct finished cell and achieve monolithic serial interconnection with adjacent cells.

MKS Solutions for Perovskite Solar Cell Processing

Challenges in Perovskite Processing MKS Solutions
Selective removal of targeted materials without delamination High-power UV, green and IR lasers to ablate required materials
High power/high fluence optics to manage the lasers
Precise, repeatable control of manufacturing process Lasers with versatile and consistent pulse control
Power meters and beam profilers to ensure optimal laser output
Robust, stable optical mounts
Preventing collateral damage, contamination or particle generation Ultrafast lasers for highest quality micromachining
Scaling capacity at larger surface areas High-power lasers for more operations

Your Partner for Perovskite Solar Cell Processing

  • 50+ years and thousands of laser micromachining systems for industrial applications
  • Long-term partner to photovoltaic processing companies
  • Full range of products: lasers, optics, opto-mechanics, beam analysis
    • Custom capabilities
    • Product availability
  • Ability to scale with you
  • Global corporation and presence

    Lasers
    Beam Analysis
    Optics
    Opto-Mechanics
    • Ultrafast (femtosecond and picosecond) and nanosecond lasers
    • DPSS Q-switched lasers
    • UV, green and IR lasers
    • Laser thermal sensors
    • Beam profilers
    • Laser power/energy meters
    • High energy mirrors
    • High energy lenses
    • High energy beamsplitters
    • Zero order waveplates
    • UV, visible and IR optics
    • Mirror mounts
    • Lens positioners
    • Prism mounts
    • Posts and pedestals
    • Manual positioners

    Lasers

    Criteria for Selecting Lasers

    When choosing a laser, there are several criteria to consider. First is the application or function of the laser – for Perovskite solar cell manufacturing, it is patterning by ablation, and more specifically, sequential removal of thin film by ablation. Next, the requirements of the application must be addressed, including the type and thickness of the material to be processed. For Perovskite solar cells, this includes not only Perovskite but also hole-transport, electron-transport, top electrode, back contact and glass coating materials whose thicknesses will be on the order of microns. Then, the specifications of lasers, such as wavelength and power, must be evaluated. Listed here are the criteria that MKS believes are most important when selecting lasers for Perovskite solar cell processing.

    • Application Requirements
      • Function
      • Type of Material & Thickness
      • Speed
      • Resulting Size of Heat Affected Zone (HAZ)
    • Laser Specifications
      • Wavelength
      • Power
      • Pulse Width and Repetition Rate
      • Stability

Perovskite Solar Cell Processing Lasers

IceFyre®
Wavelengths UV Green IR IceFyre_1064-50
Power Up to >50 W
Pulse Width <12 ps <15 ps
Repetition Rates Single Shot to 10 MHz
Max Pulse Energy Up to >60 µJ Up to >100 µJ Up to >200 µJ
Power Stability <1%, 1 σ, over 8 hours
Other Features 24/7 industrial reliability
TimeShift™ technology for pulse control
Laser/controller in single, compact package
IceFyre® FS
Wavelengths UV IR IceFyre fs
Power >50 W @ 1 & 1.25 MHz >200 W @ 1-50 MHz
Pulse Width <500 fs
Repetition Rates Single Shot to 3 MHz Single Shot to 50 MHz
Max Pulse Energy >50 µJ @ 1 MHz >200 µJ @ 1 MHz
Power Stability <1% rms over 8 hours (after warm-up)
Pulse-to-Pulse Energy Stability <2% rms
Other Features 24/7 industrial reliability
TimeShift™ technology for pulse control
Laser/controller in single, compact package
Talon® Ace™
Wavelengths UV Talon Ace
Power >100 W
Pulse Width <2 or 50 ns
Pulse Energy >500 µJ
Repetition Rates Single shot to 5 MHz
Pulse-to-Pulse Energy Stability <3%, 1 σ
Other Features 24/7 industrial reliability
TimeShift technology for pulse control
Laser/controller in single, compact package
Talon®
Wavelengths UV Green Talon
Power >45 W >70 W 
Pulse Width <25 or 35 ns <25 or 43 ns
Pulse Energy Up to 500 µJ Up to 1000 µJ
Repetition Rates 0 to 500 kHz 0 to 700 kHz
Pulse-to-Pulse Energy Stability <5% rms
Other Features 24/7 industrial reliability
E-Pulse™ technology for superb stability
Laser/controller in single, compact package
  • Explorer One: The most compact UV and green nanosecond lasers in its class with high peak power and short pulse widths.
Explorer One Explorer One XP Explorer One HP
Wavelength UV, Green UV
Power Up to 2 W 2 W (UV) or 5 W (green)  >4 or >6 W
Pulse Width <5, <10 or <15 ns <10 ns  (UV) or <12 ns (Green) <12 or <15 ns
Repetition Rates Single shot to 200 kHz Single shot to 500 kHz Single shot to 200 or 500kHz
M2 <1.3, TEM00
Stability <2%
Other Features It’s in the Box™ design
Very compact, lightweight air-cooled designs
Thousands of hours in the field

Lasers for PV Perovskite Processing Selection Guide

Presented here is a summary of recommended MKS lasers for various Perovskite manufacturing applications. Please use this as a reference guide only, and always contact us to discuss your application and requirements in detail so that we may provide the best solution for you.

IceFyre® IceFyre® FS Talon® Ace Talon® Explorer® One
Material UV
(ps)		 Green
(ps)		 IR
(ps)		 UV
(fs)		 IR
(fs)
Perovskite ✓ ✓ ✓ ✓ ✓ ✓
Hole-transport materials
(e.g., Sprio-MeOTAD, NiOx)		 ✓ ✓ ✓ ✓ ✓ ✓
Electron-transport materials
(e.g., TiO2, ZnO)		 ✓ ✓ ✓ ✓ ✓ ✓
Top electrode / back contact materials
(e.g., Ag, Pt, Au)		 ✓ ✓ ✓ ✓ ✓ ✓
Coatings from glass surface
(e.g., ITO, FTO)		 ✓ ✓

Laser Beam Analysis

Even with the advantages that lasers provide over traditional tools, lasers systems can degrade over time, leading to reduced output power or a change in focus. This, in turn, could result in lower quality laser operations. Therefore, it is very important to monitor your laser beam frequently, and the critical parameters of the laser should be checked before and after each important step of the laser manufacturing process.

Figure 1. As the laser emerges from the laser source (left), it runs through a variety of laser delivery components, such as free-space optics and process fibers, which can change the power levels and beam profile (center). The laser beam next moves through the laser processing head. Mirrors and lenses and cover glass can also have a significant impact on power levels, size, and shape (right).

Laser Power Sensors

MKS offers a comprehensive portfolio of power sensors. Shown here are examples of sensors designed to measure optical output power of short-pulsed lasers, such as IceFyre, Talon and Explorer One that operate in fs, ps and ns pulse widths.

  • Laser Thermal Power Thermal Sensors: very high damage thresholds for hundreds of watts power measurement.
F150(200)A-CM-16 30(150)A-SV-17 F80(120)A-CM-17
Spectral Range 0.248-9.4 µm 0.19-11 µm 0.248-9.4 µm laser-power-energy-meters
Power Range 300 mW - 200 W 100 mW - 150 W 100 mW - 120 W
Energy Range 50 mJ – 200 J 50 mJ – 300 J 50 mJ – 200 J
Max Avg Power Density 35 kW/cm2 60 kW/cm2 35 kW/cm2
Max Energy Density (2 msec) 45 J/cm2 50 J/cm2 45 J/cm2
Aperture Ø16 mm Ø17 mm Ø17.5 mm
Response Time 3 sec 1.7 sec 2 sec
Other Features Not water-cooled

Power Meters

Ophir laser power and energy meters work on the smart plug principle. This means that almost any power meter can work – plug and play – with almost any of the wide range of Ophir optical sensors.

Power Meters Virtual Power Meters
centauri
Centauri		 StarBright
StarBright Handheld		 Juno+
Juno+		 EA-1
EA-1
  • Extensive graphic displays on 7-in full color touchscreen display
  • Advanced measurement processing
  • Single- or dual-channel versions
  • USB and RS-232 interfaces, with user-friendly software application
  • Analog and TTL output
  • External trigger input
  • Portable use
  • For transmission checks "in the field"
  • Variety of measurement modes and displays
  • USB & RS-232 interfaces
  • USB connection to use PC as monitor
  • User-friendly software
  • Extensive graphic displays of data
  • Advanced measurement processing
  • Data logging
  • Ethernet adapter enables remote control and monitoring of sensor
  • Telnet, HTTP and UDP protocols supported
  • Interact with sensor through custom software or MKS user-friendly software
  • Data logging

Beam Profilers

SP932U
SP932U
Spectral Range 190-1100 nm
Damage Threshold 50 W/cm2, 1 J/cm2, <100 ns pulse width
Beam Sizes 34.5 µm to 5.3 mm
Pixels 2048 x 1536 Effective Pixels, 3.45 µm Pixel Size
PC Interface USB 2.0
Other Features BeamGage® software included
UltraCal™ correction algorithm
Measures cross-sectional intensity
72 dB true dynamic resolution
24 Hz frame rate in 12-bit mode

Optics

Criteria for Selecting Optics

  • Wavelength
  • Laser Damage Threshold
    • Substrate Material
    • Coating
  • Reflectivity/Transmission
  • Size and Shape

High-Energy Laser Mirrors

High-energy laser mirrors optimized for 355, 532 and 1064 nm offer very high reflectivity and damage thresholds, and standard broadband metallic mirrors offer a more economic option for good performance and value over very broad spectral ranges.

High-Energy Laser Mirrors
Wavelength 355 nm 532 nm 1064 nm
CW Damage Threshold 3 kW/cm2
Pulsed Damage Threshold 3.5 J/cm2 @ 10 ns, 20 Hz 10 J/cm2 @ 20 ns, 20 Hz 45 J/cm2 @ 10 ns, 20 Hz
Reflectivity Rs > 99.7%
Rp > 99%
Diameter 1 and 2 inch
Substrate Material UV Grade Fused Silica
Angle of Incidence 45°

High-Energy Plano-Convex Lenses

High-energy lenses optimized for 355, 532 and 1064 nm offer very high transmission and damage thresholds, and standard fused silica lenses offer good performance and value over very broad spectral ranges.

High-Energy Spherical Lenses
Wavelength 355 nm 532 nm 1064 nm
Pulsed Damage Threshold 15 J/cm2 @ 20 ns, 10 Hz
Average Reflectivity per Surface < 0.25%
Diameter 1 inch
Substrate Material High Purity Fused Silica

Nanotexture Surface Lenses

Highest laser damage resistance and lowest reflection loss

Nanostructure Surface Fused Silica Plano-Convex Lenses
Wavelength 250 to 550 nm or 500 to 1100 nm
CW Damage Threshold 15 MW/cm2
Pulsed Damage Threshold 35 J/cm2 @ 10 ns, 1064 nm
Reflection Loss 0.1%
Diameter 0.5 in.
Shapes Plano-Convex or Plano-Concave
Substrate Material High Purity Fused Silica
Other Features Sub-λ AR nanotextures etched directly into surface (no thin film coatings)

High-Energy Polarizing Cube Beamsplitters

Optimized for 355, 532 and 1064 nm, these cubes offer high damage thresholds, efficient polarization, and high extinction ratio.

High-Energy UV Polarizing Cube Beamsplitters Laser Line Polarizing Cube Beamsplitters
Wavelength 355 nm 532 nm 1064 nm
Pulsed Damage Threshold 5 J/cm2 10 J/cm2 
Reflectivity Rs > 99% Rs > 99.5%
Transmission Tp > 90% Tp > 95%
Extinction Ratio Tp/Ts >200:1
Size 1 in. 0.5 in.
Substrate Material UV Grade Fused Silica

Other Features

Optically contacted, no cement

Zero-Order Waveplates (λ/4 and λ/2)

Very high damage threshold, low sensitivity to temperature and wavelength variation.

Zero-Order Waveplates
Wavelength 355 nm 532 nm 1064 nm
CW Damage Threshold 2 MW/cm2
Reflectivity per Surface < 0.25%
Diameter 0.5 and 1 in.
Substrate Material Quartz
Temperature Coefficient 0.0001 λ/°C
Other Features ±λ/300 retardation accuracy

Opto-Mechanics

Criteria for Selecting Optical Mounts

  • Resolution/Sensitivity
  • Long Term Stability
  • Lockable
  • Size and Shape

Optical component mounts are needed to hold and adjust optics. Long term stability and low drift is crucial. Minimizing drift caused by vibrations or thermal drift over time will ensure laser alignment to the desired spot and also reduce any potential downtime due to misalignment and errors. Having a locking mechanism on these mounts can also prevent misalignment of the beam, especially during shipping and also if anything else happens during usage.

HVM industrial mounts are recommended for robust long term usage in compact space. The Suprema® mirror mount is excellent for its stainless steel construction that gives better thermal performance than an aluminum mirror mount. Ultra-fine 254-TPI adjusters provide alignment sensitivity as low as 1.5 arc sec. For applications that are really concerned about the thermal changes that can be potentially caused by prolonged high powered laser usage, the ZeroDrift™ version will compensate for some thermal changes as well. For those mirror mounts that need to be set-and-forget for a long period of time, we recommend the MFM flexure mirror Mount. These are excellent for their small footprint so that machine size can be reduced.

Suprema
Suprema		 M-Series
M-Series
Optic Diameters 0.5, 1 and 2 in. 0.5, 1 and 2 in.
Resolution 50, 100, 127 and 254 TPI 100 TPI
Angular Range ±7° ±4°
Material Stainless Steel Aluminum
Drive Types Knob
Hex Key
Exchangeable Actuators		 Knob
Hex Key
Lockable Versions Yes No
Other Versions Clear-Edge
Front- and Rear-Loading
Right- and Left-Handed
Low Wavefront Distortion
ZeroDrift™		 Clear-Edge
Front- and Rear-Loading
Right- and Left-Handed
HVM-Series
HVM-Series		 MFM-Series
MFM-Series
Optic Diameters 0.5, 1 and 2 in. 0.5, 0.75 and 1 in.
Resolution 80 and 100 TPI 80 and 100 TPI
Angular Range ±2.5°, ±3° and ±3.5° ±2.5°
Material Anodized Aluminum, Stainless Steel Stainless Steel
Drive Types Hex Key Hex Key
Lockable Versions Yes No
Other Features Front- and Rear-Loading Versions Shock Resistant
Front- and Rear-Loading Versions
Adhesive wells for permanent mounting
A-Line
A-Line		 Compact
Compact		 LP-Series
LP-Series
Optic Diameters 0.5 to 3 in. 0.5, 1 and 2 in. 0.5, 1 and 2 in.
Resolution - 100 TPI 100 TPI
Adjustments Fixed XY, XYZ, XYZθxθy XY, XYZ, XYZθxθy
Material Aluminum Aluminum Aluminum
Other Features Self-aligning design
Large clear aperture
Compatible with A-Line alignment system		 Adapters for other optics
Lockable positions		 Zero-freeplay XY mechanism
True Gimbal adjustments
Independent non-influencing locks
Adapters for other optics
UGP-1
UGP-1		 RSP-Series
RSP-Series
Optic Size 0.5 and 1 in. cube 1 and 2 in.
Resolution 100 TPI 4 arc min
Angular Range ±5° 360°
Material Aluminum Aluminum
Drive Types Knob w/ Hex Hole Coarse: knurled edge
Fine: knob
Lockable Yes Yes
Other Features True gimbal motion
Adapters for other optics		 Full ball bearing races
Adapters for other optics
Ultralign
Ultralign		 SDS Low-Profile
SDS Low-Profile
Travel Range 13 and 25 mm 10, 16 and 25.4 mm
Axes of Travel X, Z, XY, XZ and XYZ X, Z, XY and XYZ
Angular Deviation <100 µrad Pitch: <100 µrad
Yaw: <150 µrad
Bearings Crossed-Roller Ball (Gothic Arch Bearing Ways)
Material Stainless Steel Stainless Steel
Drive Type Adjustment Screw
Micrometer
Motorized Actuator		 Side-Mounted Micrometer
Lockable Yes Yes
Other Features Extra thick plates for more stability
Low profile
Right- and left-handed configurations		 <20 mm height
Non-influencing locking mechanism
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