As a new semiconductor material, perovskite has the advantages of high absorption efficiency in visible light, low defect density and long carrier diffusion distance. Lead halide perovskite has photovoltaic characteristics and high photoelectric conversion efficiency (currently, its conversion efficiency has been improved to about 21%). In addition, lead halide perovskite can also convert electrical energy into light, so it can also be used to make light-emitting diodes (LEDs) used in lighting or displays, and even lasers. If the organic lead halide perovskite is made small enough to become nanocrystals, it could also become a transmitter that emits a single photon at a time, which could be used in optical quantum computers.
1.Design and research for LED based on organic optoelectronic materials
Figure 1 White organic light-emitting diodes based on a single emissive layer (upper). Light-emitting diodes based on perovskite nanocrystals (lower).
White organic light-emitting diode (WOLED) technology has attracted considerable attention because of its potential use as a next-generation solid-state lighting source. However, most of the reported WOLEDs that employ the combination of multi-emissive materials to generate white emission may suffer from color instability, high material cost, and a complex fabrication procedure which can be diminished by the single-emitter-based WOLED. Herein, a colortunable material, tris(4-(phenylethynyl)phenyl)amine (TPEPA), is reported. by precisely controlling the annealing time and temperature, a white-light OLED is fabricated with the maximum external quantum effciency of 3.4% with TPEPA as the only emissive molecule. As far as it is known, thus far, this is the best performance achieved for single small organic molecule based WOLED devices.
Organic–inorganic hybrid perovskite materials with mixed cations have demonstrated tremendous advances in photovoltaics recently, by showing a signifcant enhancement of power conversion effciency and improved perovskite stability. The recent hot research on perovskite has demonstrated tremendous advances in photoelectronic devices. HC(NH2)2 (FA) cation based perovskite is rarely studied, espectially FA-based perovskite LEDs. Inspired by the great achievement of mixed-cation perovskite solar cells, we have synthesized mixed-cation perovskite (FA(1−x)CsxPbBr3) NCs and successfully demonstrated bright and efficient LEDs.
2.Design and research on perovskite micro-nano laser.
Figure 2 The laser characters of CH3NH3PbBr3 perovskite crystals.
Lead halide perovskite-based lasers have attracted much research attention due to their tunable emission colors, high gain coefficient and low threshold. Here, we demonstrated a facile solution method via temperature modulation to synthesize CH3NH3PbBr3 perovskite crystals with sub-circular and quasi-cubic shapes for whispering gallery resonant mode and Fabry-Pérot mode lasing emission, respectively. A low lasing threshold of 6.4 μJ/cm2 and a full width at half maximum of 0.7 nm in an individual sub-circular cavity can be achieved at room temperature. In the quasi-cubic cavities, the Fabry-Pérot lasing oscillation modes not only exist in the horizontal directions, but also in the vertical directions according to the adjustment of optical pumped method. The lasing thresholds and linewidths are in the range of 14 ~ 25 μJ/cm2 and 0.18 ~ 0.51 nm, respectively. This work may create the possibilities for cavity design and fabrication of perovskite lasers in the future potential applications.