Large perovskite crystals improve carrier mobility for field-effect transistors
Large perovskite crystals improve carrier mobility for field-effect transistors lead image
Metal Halide perovskites demonstrate impressive power conversion efficiency in photovoltaic devices but many of their physical properties are still elusive. Researchers have investigated perovskite as an efficient polycrystalline semiconductor for field-effect transistors (FETs) for 20 years. Though performance has improved during that time, its potential is limited by problems, such as low carrier mobilities, caused by grain boundaries and structural disorder in the polycrystalline films.
Hoping to overcome these problems, Matsushima et al. built and tested a FET using large crystals of 2-phenethylammonium tin iodide perovskite, (PEA)2SnI4.
“Our large-crystal FETs demonstrated the highest carrier mobilities ever reported in any perovskite FET,” said author Toshinori Matsushima.
The researchers synthesized large perovskite crystals by cooling overnight a solution containing phenethylammonium iodide and tin (II) iodide. The crystals displayed rough surfaces which the team exfoliated by applying scotch tape to each side and pulling away any residue. To fabricate FETs, the researchers laminated the large, exfoliated crystals onto substrates with source/drain electrodes.
Contrary to common belief that tin-based perovskite devices are unstable, the team found their tin-based FETs showed good stability even in air. By using tin, their device holds another advantage over most other perovskite FETs.
“Most reported perovskite solar cells and FETs contain harmful lead,” said Matsushima. “Our tin-based perovskite FETs are completely lead free.”
Although the researchers found significant improvement in the carrier mobility of the crystal, they were unable to establish good contact between the perovskite crystal and substrate, which severely lowered the overall yield of the device. They hope to overcome this challenge in the future.
“We are now aiming at growing high-quality perovskite films without grain boundaries directly on substrates for FET application,” said Matsushima.
Source: “Large metal halide perovskite crystals for field-effect transistor applications,” by Toshinori Matsushima, Matthew R. Leyden, Takashi Fujihara, Chuanjiang Qin, Atula S. D. Sandanayaka, and Chihaya Adachi, Applied Physics Letters (2019). The article can be accessed at https://doi.org/10.1063/1.5116411 .
