Home > Press > Meniscus-assisted technique produces high efficiency perovskite PV films
![]() |
This is an optical micrograph of perovskite crystal grains crafted by meniscus-assisted solution printing. CREDIT Image courtesy of Ming He, Georgia Tech |
Abstract:
A new low-temperature solution printing technique allows fabrication of high-efficiency perovskite solar cells with large crystals intended to minimize current-robbing grain boundaries. The meniscus-assisted solution printing (MASP) technique boosts power conversion efficiencies to nearly 20 percent by controlling crystal size and orientation.
The process, which uses parallel plates to create a meniscus of ink containing the metal halide perovskite precursors, could be scaled up to rapidly generate large areas of dense crystalline film on a variety of substrates, including flexible polymers. Operating parameters for the fabrication process were chosen by using a detailed kinetics study of perovskite crystals observed throughout their formation and growth cycle.
"We used a meniscus-assisted solution printing technique at low temperature to craft high quality perovskite films with much improved optoelectronic performance," said Zhiqun Lin, a professor in the School of Materials Science and Engineering at the Georgia Institute of Technology. "We began by developing a detailed understanding of crystal growth kinetics that allowed us to know how the preparative parameters should be tuned to optimize fabrication of the films."
The new technique is reported July 7 in the journal Nature Communications. The research has been supported by the Air Force Office of Scientific Research (AFOSR) and the National Science Foundation (NSF).
Perovskites offer an attractive alternative to traditional materials for capturing electricity from light, but existing fabrication techniques typically produce small crystalline grains whose boundaries can trap the electrons produced when photons strike the materials. Existing production techniques for preparing large-grained perovskite films typically require higher temperatures, which is not favorable for polymer materials used as substrates - which could help lower the fabrication costs and enable flexible perovskite solar cells.
So Lin, Research Scientist Ming He and colleagues decided to try a new approach that relies on capillary action to draw perovskite ink into a meniscus formed between two nearly parallel plates approximately 300 microns apart. The bottom plate moves continuously, allowing solvent to evaporate at the meniscus edge to form crystalline perovskite. As the crystals form, fresh ink is drawn into the meniscus using the same physical process that forms a coffee ring on an absorbent surface such as paper.
"Because solvent evaporation triggers the transport of precursors from the inside to the outside, perovskite precursors accumulate at the edge of the meniscus and form a saturated phase," Lin explained. "This saturated phase leads to the nucleation and growth of crystals. Over a large area, we see a flat and uniform film having high crystallinity and dense growth of large crystals."
To establish the optimal rate for moving the plates, the distance between plates and the temperature applied to the lower plate, the researchers studied the growth of perovskite crystals during MASP. Using movies taken through an optical microscope to monitor the grains, they discovered that the crystals first grow at a quadratic rate, but slow to a linear rate when they began to impinge on their neighbors.
"When the crystals run into their neighbors, that affects their growth," noted He. "We found that all of the grains we studied followed similar growth dynamics and grew into a continuous film on the substrate."
The MASP process generates relatively large crystals - 20 to 80 microns in diameter - that cover the substrate surface. Having a dense structure with fewer crystals minimizes the gaps that can interrupt the current flow, and reduces the number of boundaries that can trap electrons and holes and allow them to recombine.
Using films produced with the MASP process, the researchers have built solar cells that have power conversion efficiencies averaging 18 percent - with some as high as 20 percent. The cells have been tested with more than 100 hours of operation without encapsulation. "The stability of our MASP film is improved because of the high quality of the crystals," Lin said.
Doctor-blading is one of the conventional perovskite fabrication techniques in which higher temperatures are used to evaporate the solvent. Lin and his colleagues heated their substrate to only about 60 degrees Celsius, which would be potentially compatible with polymer substrate materials.
So far, the researchers have produced centimeter-scale samples, but they believe the process could be scaled up and applied to flexible substrates, potentially facilitating roll-to-roll continuous processing of the perovskite materials. That could help lower the cost of producing solar cells and other optoelectronic devices.
"The meniscus-assisted solution printing technique would have advantages for flexible solar cells and other applications requiring a low-temperature continuous fabrication process," Lin added. "We expect the process could be scaled up to produce high throughput, large-scale perovskite films."
Among the next steps are fabricating the films on polymer substrates, and evaluating other unique properties (e.g., thermal and piezotronic) of the material.
###
This research was supported by the Air Force Office of Scientific Research (MURI FA9550-14-1-0037; FA9550-16-1-0187) and National Science Foundation (CMMI-1562075). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the sponsoring agencies.
####
For more information, please click here
Contacts:
John Toon
404-894-6986
Copyright © Georgia Institute of Technology
If you have a comment, please Contact us.Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
Related Links |
Related News Press |
News and information
Controlling chemical catalysts with sculpted light January 15th, 2021
Perovskites
CsPbBrI2 perovskites with low energy loss for high-performance indoor and outdoor photovoltaics December 1st, 2020
Lead-free magnetic perovskites November 6th, 2020
Aberrant electronic and structural alterations in pressure tuned perovskite NaOsO3 September 18th, 2020
Crystal structure discovered almost 200 years ago could hold key to solar cell revolution July 3rd, 2020
Govt.-Legislation/Regulation/Funding/Policy
Controlling chemical catalysts with sculpted light January 15th, 2021
Researchers realize efficient generation of high-dimensional quantum teleportation January 14th, 2021
Chemists invent shape-shifting nanomaterial with biomedical potential It converts from sheets to tubes and back in a controllable fashion January 13th, 2021
Possible Futures
Scientists' discovery is paving the way for novel ultrafast quantum computers January 15th, 2021
Physicists propose a new theory to explain one dimensional quantum liquids formation January 15th, 2021
Controlling chemical catalysts with sculpted light January 15th, 2021
Discoveries
Physicists propose a new theory to explain one dimensional quantum liquids formation January 15th, 2021
Materials/Metamaterials
Chemists invent shape-shifting nanomaterial with biomedical potential It converts from sheets to tubes and back in a controllable fashion January 13th, 2021
USTC develops ultrahigh-performance plasmonic metal-oxide materials January 11th, 2021
Stretching diamond for next-generation microelectronics January 5th, 2021
Microfabricated elastic diamonds improve material's electronic properties January 1st, 2021
Announcements
Controlling chemical catalysts with sculpted light January 15th, 2021
Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters
Controlling chemical catalysts with sculpted light January 15th, 2021
Military
Stretching diamond for next-generation microelectronics January 5th, 2021
Spontaneous robot dances highlight a new kind of order in active matter January 1st, 2021
Printing/Lithography/Inkjet/Inks/Bio-printing/Dyes
Weak force has strong impact on nanosheets: Rice lab finds van der Waals force can deform nanoscale silver for optics, catalytic use December 15th, 2020
Materials scientists learn how to make liquid crystal shape-shift September 25th, 2020
New printing process advances 3D capabilities: Technology aims to improve quality of products used in business, industry and at home July 31st, 2020
![]() |
||
![]() |
||
The latest news from around the world, FREE | ||
![]() |
![]() |
||
Premium Products | ||
![]() |
||
Only the news you want to read!
Learn More |
||
![]() |
||
Full-service, expert consulting
Learn More |
||
![]() |