An electron-transport polymer with good solution processibility, excellent thermal stability, and high electron affinity based on alternating perylene diimide and dithienothiophene units has been synthesized. Electron mobilities as high as 1.3 × 10-2 cm2 V-1 s-1 have been measured in field-effect transistor geometry. The polymer shows broad absorptions throughout the visible and extending into the near-IR. A power conversion efficiency of over 1%, under simulated AM 1.5, 100 mW/cm2, was measured for a single-layer solar cell using this polymer as an acceptor and a polythiophene derivative as a donor.

Carbon quantum dots (CQDs) have emerged as promising materials for optoelectronic applications on account of carbon’s intrinsic merits of high stability, low cost, and environment-friendliness. However, the CQDs usually give broad emission with full width at half maximum exceeding 80 nm, which fundamentally limit their display applications. Here we demonstrate multicolored narrow bandwidth emission (full width at half maximum of 30 nm) from triangular CQDs with a quantum yield up to 54–72%. Detailed structural and optical characterizations together with theoretical calculations reveal that the molecular purity and crystalline perfection of the triangular CQDs are key to the high color-purity. Moreover, multicolored light-emitting diodes based on these CQDs display good stability, high color-purity, and high-performance with maximum luminance of 1882–4762 cd m−2 and current efficiency of 1.22–5.11 cd A−1. This work will set the stage for developing next-generation high-performance CQDs-based light-emitting diodes.