Polymer Light-Emitting Electrochemical Cells for High-Efficiency Low-Voltage Electroluminescent Devices

Transient and d.c. analysis of the operation mechanism of light-emitting electrochemical cells

“…The main feature of a LEC is that the active layer comprises a blend of a conjugated electroluminescent polymer (EP) and a polymer electrolyte, which confers to them advantageous characteristics like bipolar operation (in forward or in reverse bias) and low operating voltages, regardless of the work function of the electrodes and of the thickness of the active layer [7]. On the other hand, LECs have some drawbacks as slow response time, imposed by the low ionic mobility, lower voltage stability (a) Present address: Universidade Estadual Paulista -UNESP -Rua Cristóvão Colombo, 2265, 15054-000, São José do Rio Preto, SP, Brazil; E-mail: lucas@sjrp.unesp.br and shorter lifetime [13], which limit their technological applications. Moreover, there is still a lot of discussion about the fundamental operation mechanism of LECs, which is not completely understood until now.…”

On-demand photochemical stabilization of doping in light-emitting electrochemical cells

“…[12][13][14] The light-emitting electrochemical cell (LEC) comprises a blend of a conjugated polymer and mobile ions as the active material sandwiched between two electrodes. [15][16][17][18][19][20][21][22][23][24][25] An LEC actually makes use of the mobility of the ions for the in-situ electrochemical formation of doped conjugated polymer regions at the electrode interfaces, and the subsequent establishment of a light-emitting p-n junction within the bulk of the active material, under the direction of an externally applied voltage. [26,27] However, the pn junction in LECs is dynamic and only stable as long as the applied voltage remains, and for applications where a fast, repeatable response and rectification of current and light emission are required this represents a problem.…”

The dynamic organic p–n junction

“…[23][24][25][26][27][28][29][30] These ions rearrange during operation, which in turn allows for a range of attractive device properties, including low-voltage operation with thick active layers and stable electrode materials. [31][32][33][34][35][36] However, the further development of LECs is currently hampered by an inadequate understanding of the device operation. In fact, an active debate regarding the fundamental nature of LEC operation has continued for more than a decade, and two distinct models are competing for acceptance: the electrochemical doping model 18,32,[37][38][39][40] and the electrodynamic model 36,[41][42][43][44] .…”