Sunday, November 9, 2014

Conformal organohalide perovskite laser by realized ALD

As reported by Nanotechweb : Researchers at the University of Toronto in Canada say that they have made the first perovskite-based spherical resonator laser by coating organometallic halide perovskites uniformly onto glass microspheres. The device might be employed in novel optical communications applications, and the new structure also shows promise for solar cells and photodetectors.

Obviously it has been done by ALD!

The Toronto team, led by Edward Sargent, employed an industry-standard technique, known as atomic layer deposition (ALD), to grow high-quality one-atom seed layers of lead sulphide and then developed a way to “exchange” these PbS layers with perovskite by exposing them to iodine gas vapour and methylammonium iodide. The resulting structure – a highly pure, polycrystalline film of CH3NH3PbI3 perovskite – can then be coated onto a spherical optical cavity made from a glass microsphere (see figure). This optical cavity lases when pumped with green, red or blue light.

Check out the full story here and the paper below.

Brandon R. Sutherland , Sjoerd Hoogland, Michael M. Adachi, Chris T. O. Wong, and Edward H. Sargent
ACS Nano, 2014, 8 (10), pp 10947–10952

Conformal integration of semiconductor gain media is broadly important in on-chip optical communication technology. Here we deploy atomic layer deposition to create conformally deposited organohalide perovskites—an attractive semiconducting gain medium—with the goal of achieving coherent light emission on spherical optical cavities. We demonstrate the high quality of perovskite gain media fabricated with this method, achieving optical gain in the nanosecond pulse regime with a threshold for amplified spontaneous emission of 65 ± 8 μJ cm–2. Through variable stripe length measurements, we report a net modal gain of 125 ± 22 cm–1 and a gain bandwidth of 50 ± 14 meV. Leveraging the high quality of the gain medium, we conformally coat silica microspheres with perovskite to form whispering gallery mode optical cavities and achieve lasing

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