Department of Physics, Yunnan University, Kunming, Yunnan 650091, People's Republic of China.
Yunnan Key Laboratory for Micro/Nano Materials and Technology, Yunnan University, Kunming, Yunnan 650091, People's Republic of China.
Sci Rep. 2017 Feb 22;7:43130. doi: 10.1038/srep43130.
Tandem device is an important architecture in fabricating high performance organic light-emitting diodes and organic photovoltaic cells. The key element in making a high performance tandem device is the connecting materials stack, which plays an important role in electric field distribution, charge generation and charge injection. For a tandem organic light-emitting diode (OLED) with a simple Liq/Al/MoO stack, we discovered that there is a significant current lateral spreading causing light emission over an extremely large area outside the OLED pixel when the Al thickness exceeds 2 nm. This spread light emission, caused by an inductive electric field over one of the device unit, limits one's ability to fabricate high performance tandem devices. To resolve this issue, a new connecting materials stack with a C fullerene buffer layer is reported. This new structure permits optimization of the Al metal layer in the connecting stack and thus enables us to fabricate an efficient tandem OLED having a high 155.6 cd/A current efficiency and a low roll-off (or droop) in current efficiency.
串联器件是制造高性能有机发光二极管和有机光伏电池的重要结构。制造高性能串联器件的关键要素是连接材料层，它在电场分布、电荷产生和注入方面起着重要作用。对于具有简单 Liq/Al/MoO 堆叠的串联有机发光二极管 (OLED)，我们发现当 Al 厚度超过 2nm 时，会出现明显的电流横向扩展，导致 OLED 像素外的极大面积发光。这种由器件单元之一的感应电场引起的扩展发光限制了人们制造高性能串联器件的能力。为了解决这个问题，我们报告了一种具有 C60 富勒烯缓冲层的新型连接材料层。这种新结构允许优化连接堆叠中的 Al 金属层，从而使我们能够制造出具有高效率的串联 OLED，其电流效率高达 155.6cd/A，电流效率下降（或衰减）低。
