Optical Properties of Crystalline Thin Films of the Organic Laser Gain Material 4,4′-Bis[(N-carbazole)styryl]biphenyl

Abstract

Enhancing photoluminescence quantum yield and excellent transport associated with molecular order are important for advancing organic laser device performance. However, materials combining excellent quantum yield and transport are rare. 4,4′-Bis­[(N-carbazole)­styryl]­biphenyl (BSB-Cz) has been heavily investigated as a promising material for laser devices. However, research on highly ordered BSB-Cz crystalline films is lacking, despite the much better transport properties to be expected. Here, we show that BSB-Cz thin-film crystals can be prepared using a simple vacuum deposition method, followed by thermal annealing. The resulting crystalline neat BSB-Cz thin films show a very high photoluminescence quantum yield of over 85% and superior optical stability compared to amorphous BSB-Cz films under intense pumping conditions. We believe that our work provides a route for advancing organic laser devices through introducing crystallinity in emitter thin films with a scalable approach.

Highly Ordered Small Molecule Organic Semiconductor Thin-Films Enabling Complex, High-Performance Multi-Junction Devices

“…However, achieving an electrically driven organic laser has proven to be challenging, mainly due to the lack of materials systems possessing both excellent charge transport and efficient emission properties. 4,4′-Bis­[( N -carbazole)­styryl]­biphenyl (BSB-Cz), which displays excellent optical properties and a low threshold for achieving lasing, has been shown to be a promising candidate for electrically driven lasers, with which the Adachi group has observed indication of current-induced lasing using amorphous BSB-Cz thin-films. , Wang et al has reported on the growth of an organic laser gain material, BSB-Cz thin-film crystals, and studied their optical properties . For the crystalline BSB-Cz thin-films, both the photoluminescence quantum yield and optical stability are improved relative to those of its amorphous counterpart.…”

“…116,119 Wang et al has reported on the growth of an organic laser gain material, BSB-Cz thin-film crystals, and studied their optical properties. 120 For the crystalline BSB-Cz thin-films, both the photoluminescence quantum yield and optical stability are improved relative to those of its amorphous counterpart. It would therefore be interesting to integrate BSB-Cz thin-film crystals into laser devices.…”