Towards complete linearly-polarized electroluminescence using isotropic emitters

Linearly polarized (LP) light sources are essential components in numerous applications. Solution-processed LP light-emitting diodes (LP-LEDs) based on perovskite and colloidal nanocrystals offer a promising route for low-cost and direct LP light generation. However, the performance of these devices is limited by the conventional method of aligning anisotropic emitters, such as nanorods and nanoplatelets, which faces inherent challenges in achieving high anisotropy and precise alignment necessary for high polarization ratio (PR) emission. Here, we introduce a paradigm shift by decoupling polarization control from the emitter’s intrinsic anisotropy. We demonstrate near-complete LP electroluminescence through the integration of isotropic colloidal quantum dot (QD) emitters into an anisotropic vertical microcavity. This architecture leverages the cavity-induced polarization-splitting effect to create a narrow window for extracting a single polarization mode. The resulting QD-based LP-LEDs achieve a record experimental PR of 351, a fifty-fold improvement over the previous benchmark for solution-processed counterparts (6.8), rivaling the performance of any existing LP-LED system. This work provides a robust and universally applicable platform that circumvents the long-standing limitations associated with aligning anisotropic emitters, enabling the use of arbitrary emitters to achieve advanced LP-LEDs with superior performance.