Photomultiplication in NIR Organic Diodes

Nature publishes a paper "Enhancing sub-bandgap external quantum efficiency by photomultiplication for narrowband organic near-infrared photodetectors" by Jonas Kublitski, Axel Fischer, Shen Xing, Lukasz Baisinger, Eva Bittrich, Donato Spoltore, Johannes Benduhn, Koen Vandewal, and Karl Leo from Technische Universität Dresden (Germany), Leibniz-Institut für Polymerforschung Dresden (Germany) and Hasselt University (Belgium).

"Photomultiplication-type organic photodetectors have been shown to achieve high quantum efficiencies mainly in the visible range. Much less research has been focused on realizing near-infrared narrowband devices. Here, we demonstrate fully vacuum-processed narrow- and broadband photomultiplication-type organic photodetectors. Devices are based on enhanced hole injection leading to a maximum external quantum efficiency of almost 2000% at −10 V for the broadband device. The photomultiplicative effect is also observed in the charge-transfer state absorption region. By making use of an optical cavity device architecture, we enhance the charge-transfer response and demonstrate a wavelength tunable narrowband photomultiplication-type organic photodetector with external quantum efficiencies superior to those of pin-devices. The presented concept can further improve the performance of photodetectors based on the absorption of charge-transfer states, which were so far limited by the low external quantum efficiency provided by these devices."