AFRL Researchers Inspired by Newsprint Use 3D Printing and Perovskites to Fabricate Cost-Efficient Solar Cells

A friend told me once that it was possible to make an inexpensive, working solar oven just by painting a big cardboard box black and lining the inside with tinfoil, then dragging it out into the yard to use on a very sunny day. Solar energy is pretty powerful, and it can be used to power 3D printed rowboats, cars, scooters, and even 3D printers themselves. While we’ve seen 3D printed solutions used to collect solar power, researchers at the Air Force Research Laboratory (AFRL), which is housed at Wright Patterson Air Force Base (WPAFB) in Ohio, are looking to additive manufacturing technology to make solar cells more cost efficient, as the current process to make solar cells is expensive, difficult, and time-consuming.

Engineers who make solar cells use extremely pure, single-crystalline silicon, which is extracted from materials like sand or quartz before being turned into flat wafers. An electric field, with negative and positive polarity, is formed by chemically treating these wafer semiconductors, which are enclosed in a support to make a photovoltaic module. Only then are the solar cells able to collect sunlight and transform it into electricity. Not only does this complex, multi-step process take a long time, it requires technicians and sophisticated equipment; this leads us to ever-important quality control testing, because any manufacturing discrepancy could have a negative impact on the solar cells’ performance.

“Sun is abundant, and it’s free. Solar cells can generate electricity in an environmentally friendly way, but current, complex fabrication costs make the technology expensive,” explained Dr. Santanu Bag, a project scientist at the AFRL’s Materials and Manufacturing Directorate. “We’re looking at new ways to use materials and manufacturing technologies to make these less expensively.”

Even though solar power itself has the potential to cut back on costs overall, the high manufacturing costs related to the technology makes it less available. That’s why Dr. Bag and his team are researching different methods to increase the cost efficiency of solar cells, which will also boost potential applications for solar energy.

Dr. Bag said, “If you want to make solar competitive, you need to make solar cells more efficient and cost effective.”

Interestingly, the research team was first inspired by newsprint, where ink is printed onto rolls of blank paper to create newspapers. Then, they began to look for printable materials, other than inorganic silicon, that could turn solar into energy. Dr. Bag landed on thin-film perovskites, which we’ve seen combined with 3D printing technology before; the lightweight material was a good choice, as it has high light-absorbing capabilities, mechanical flexibility, and power conversion efficiencies, as well as being comprised of earth-abundant materials.

“Silicon cells use purely inorganic materials, which by nature are very hard. We needed a material that was easy to print and at the same time able to capture sunlight. We determined an inorganic-organic hybrid material would be easy to print and could still harvest solar energy,” explained Dr. Bag.

“The material has been around since the 1990s and was used to make test-level, light-emitting diodes. Researchers knew it had solar ability, but this was not the focus at the time.”

Dr. Bag and his colleagues, James R. Denault with the Universal Technology Corporation and AFRL’s Soft Matter Materials Branch Chief Michael F. Durstock, published a paper on the study, titled “Aerosol-Jet-Assisted Thin-Film Growth of CH3 NH3 PbI3 Perovskites-A Means to Achieve High Quality, Defect-Free Films for Efficient Solar Cells,” in the Advanced Energy Materials journal.

According to the paper, “In this work, a method for shifting perovskite solar cell fabrication away from the benchtop toward a more automated, reproducible, and potentially scalable fabrication approach is investigated. While there has been some work reported in fabricating perovskite solar cells using doctor-blading, spray-coating, inkjet-printing, and slot-die coating, few have focused on aerosol-jet deposition technology. It is shown here that aerosol-jet deposition technology is well suited to deal with the challenges associated with precisely controlling the film morphology, composition, and yield in a fully automated and reproducible way.”

Ultrasonic waves were used to atomize perovskite precursor material, in order to form very fine aerosol droplets, which were moved into the print nozzle of an aerosol-jet spray 3D printer. The direct write printer coated a surface with the material, using CAD tool paths, which formed a solar cell that had a 15.4% efficiency on a flat surface. The AFRL team also demonstrated that they could print the solar cells on a 3D surface with an efficiency of 5.4%, which has never been accomplished before with printed photovoltaics.

“We have not optimized conditions for 3-D printing of these yet, but we know it can be done,” said Dr. Bag. “Once you know how to print it, it has huge potential for other applications. Understanding ways to make and print this material more efficiently at the most basic level can lead to future cost savings.”

There are numerous applications for perovskite in the US Air Force, and for this new 3D printing process – it could be used to create self-powered robotics and light-emitting devices, print flexible solar cells on clothes, and even to fabricate flexible, self-powered sensors. The research team has filed a patent application for the technology. Discuss in the Solar Cells forum at 3DPB.com.

[Source: Phys.org]