Solution-processed semiconductor nanocrystals have attracted great interest in optoelectronics including color conversion and enrichment in quality lighting and display backlighting . In this talk, we will present types of colloidal nanocrystals obtained by tailoring and controlling the composition, size, and dimensionality of these semiconductor nanomaterials in an effort to realize high performance in light generation and lasing . Based on rational designs and control of the excitonic properties in these nanocrystals, we successfully demonstrated efficient light-emitting diodes  and lasers [4-5]. These include colloidal quantum dots, quantum rods and quantum wells. We showed that electronic-type tuning in colloidal quantum dots and rods allows for the fine tunability of the spectral position of the amplified spontaneous emission . Ultra-low threshold stimulated emission in the blue to red was achieved using engineered core/shell quantum dots enabling suppressed Auger recombination. We developed an all-colloidal laser using the nanocrystals as optical gain media. Also, we showed that the colloidal quantum wells uniquely combine ultra-low threshold stimulated emission and record high optical gain coefficients; and the excitonic properties of these colloidal quantum wells can further be tuned by controlled stacking . Furthermore, we developed large-area (> 50 ? 50 cm) freestanding sheets of nanocrystals and their integrated macrocrystals towards stable, efficient and quality solid-state lighting . These results indicate that colloidal optoelectronics holds great promise to challenge epitaxial counterparts in the near future.
 H. V. Demir et al., Nano Today 6, 632 (2011); T. Erdem and H. V. Demir, Nature Photonics 5, 126 (2011).
 B. Guzelturk et al. Laser & Photonics Reviews 8, 73 (2014); and J. Phys. Chem. Lett. 5, 2214 (2014).
 X. Yang et al., Advanced Materials 24, 4180 (2012); Advanced Functional Materials 24, 5977 (2014); ACS Nano 8, 8224 (2014); and Small 10, 246 (2014).
 A. F. Cihan et al. ACS Nano 7, 4799 (2013); and J. Phys. Chem. Lett. 4, 4146 (2013).
 B. Guzelturk et al. ACS Nano 8, 6599 (2014); and ACS Nano (2014). DOI: 10.1021/nn5053734.
 E. Mutlugun et al., Nano Letters 12, 3986 (2012); and T. Otto et al., Nano Letters 12, 5348 (2012).
This seminar is sponsored by Stanford OSA.