Tóm tắt

Organic semiconductors with optoelectronic properties have attracted intensive interests in the fields of organicrnlight-emitting diodes, organic photovoltaics and organic photodetectors. In these functional devices, excitonrnevolution is the key process. Generally, linear process is dominant that one photon is created from each injectedrnelectron-hole pair, vice versa. This linear process restricts the internal quantum efficiency to be 100% in optoelectronic devices. Alternatively, nonlinear optoelectronic processes, like triplet-triplet annihilation (TTA) andrnsinglet fission (SF), can theoretically break the limitation stated in linear optoelectronic processes. TTA and SFrnare two dynamic reversible processes, which link one high-lying energy singlet with two low-lying energy tripletrnexcitons on two neighboring chromophores. These nonlinear processes bring the possibility of novel functionsrnand application scenarios, and hence have attracted more and more attentions recently.rnThis review will systematically and comparatively summarize the basic properties of TTA and SF processes,rnand their applications in optoelectronic devices in the view of device physics. It starts with a concise introductionrnof basic knowledge of TTA and SF. Then, the characteristics used to identify these processes are described.rnSubsequently, implementing them in OLEDs are summarized, followed by the application examples in OPVs.rnEmphasis is laid on the triplet quenching mechanisms in working devices, since both TTA and SF processesrnhighly rely on triplet excitons. These discussions on the recent important progresses aim to gain some insight intornthe device physics for device engineering. Finally, a perspective is presented.