Researchers at EPFL in Switzerland have designed a standardized way to make nanowires out of perovskite, by guiding the growth of perovskite nanowires with nanofluidic channels. The researchers used a single-step, 'slip-coating' method to produce the first ever nanowires from methylammonium lead iodide, a material that has attracted attention for its ability to absorb light and produce electrical current in response.
Nanowires are extremely thin, and perovskite nanowires make outstanding candidates for the efficient transport of electrons and excitons ' the recyclable 'holes' that electrons leave behind when they move as a current. Using nanowires could increase the efficiency of solar cells, because the wires act as "direct conductive highways" to transmit current more efficiently.
The problem is that it is difficult to grow the billions of nanowires needed for applications with the exact same length and diameter. The challenge, therefore, is to control the growth of perovskite nanowires in a way that can produce a 2D surface that could be used in a solar cell. Using nanofluidic channels in an automated way, the researchers were able to produce tens of thousands of parallel nanowires on a silicon surface. The growth process was visualized in real-time with a simple optical microscope, which shed light into the crystal growth mechanism.
The technique represents a big step forward in nanowire technology. Because it is automated, it also paves the way towards fabrication of wafer-scale perovskite nanowire thin films, which are ideal for solar cells, but also for other optoelectronic devices, including lasers, light-emitting diodes (LEDs) and light detectors.
