Management and utilization of triplet excitons in organic optoelectronic devices

Organic optoelectronics have received tremendous attentions in the past few decades, which are benefitting from the rapid development of organic semiconductors and their unique merits such as flexible design, low-cost production, and rich optoelectronic properties. Triplet excitons with two parallel electronic spins generated in the organic optoelectronic devices have significant effects on the device performance. In this review, a timely summary and brief discussion of the management and utilization of the triplet excitons in organic optoelectronic devices are given. We firstly summarized the studies and applications of triplet excitons in optical-to-electrical and electrical-to-optical devices, including solar cells, organic light-emitting diodes (OLEDs) and organic light-emitting transistors (OLETs). Particularly, the pioneering advances of triplet management in OLETs are reviewed for the first time. Additionally, two possible strategies for breaking the theoretical limit of internal quantum efficiency (IQE) in electroluminescent devices by fully taking the advantages of triplet excitons are proposed. Finally, the challenges and perspective of existing issues in this field for further improving the performance of optoelectronic devices and other related research directions are also provided.