Reducing traps increases performance of organic photodetectors

January 22, 2021

Organic photodetectors (OPDs) have a huge potential for applications in low-cost imaging, health monitoring and near infrared sensing. Yet, before industrially realizing these applications, the performance of these devices still needs to be improved.

Recent research on organic photodetectors based on donor-acceptor systems has resulted in narrow-band, flexible and biocompatible devices, of which the best reach external photovoltaic quantum efficiencies of close to 100%. However, the high noise in the off state produced by these devices limits their specific detectivity, severely reducing the performance, for example measuring faint light.

Jonas Kublitski and his colleagues at the Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and the Institute of Applied Physics (IAP) at TU Dresden now found out that the high noise in the off state is a consequence of unwanted trap states distributed near the mid-gap of organic semiconductors. By measuring the amount of traps, the physicists draw a direct correlation between the characteristics of the trap states and the off state of OPDs.

Building on these results, Mr. Kublitski was able to draw a model depicting this relation:

"By modelling the dark current of several donor-acceptor systems, we reveal the interplay between traps and charge-transfer states as a source of dark current and show that traps dominate the generation processes, thus being the main limiting factor of OPD detectivity.

The newly discovered relation does only clarify the operation of OPDs but gives guidance for further research in the field. This work is a result of four years of research during my Ph.D. I am very happy to share these results, as they can refocus the attention of our field into understanding the origin of the limited performance of OPDs, which was so far unknown."
Original publication:

Kublitski, Jonas; Hofacker, Andreas; K. Boroujeni, Bahman; Benduhn, Johannes; C. Nikolis, Vasileios; Kaiser, Christina; Spoltore, Donato; Kleemann, Hans; Fischer, Axel; Ellinger, Frank; Vandewal, Koen; Leo, Karl. Reverse dark current in organic photodetectors and the major role of traps as source of noise, Nature Communications.

Technische Universität Dresden

Related Organic Semiconductors Articles from Brightsurf:

Scientists develop method to detect charge traps in organic semiconductors
Scientists at Swansea University have developed a very sensitive method to detect the tiny signatures of so called 'charge traps' in organic semiconductors.

Liquid metals come to the rescue of semiconductors
Two-dimensional semiconductors offer a possible solution to the limited potential for further shrinking of traditional silicon-based electronics: the long-predicted end of 'Moore's Law'.

Shedding light on the development of efficient blue-emitting semiconductors
Scientists at Tokyo Institute of Technology (Tokyo Tech) have discovered a new alkali copper halide, Cs5Cu3Cl6I2, that emits pure blue light.

Theoretical prediction of reverse intersystem crossing for organic semiconductors
A team of Japanese researchers developed a method to predict rate constants of reverse intersystem crossing (RISC) associated with light emission efficiency of organic semiconductors used for OLED through quantum chemical calculations with computers.

2D semiconductors found to be close-to-ideal fractional quantum hall platform
Columbia University researchers report that they have observed a quantum fluid known as the fractional quantum Hall states (FQHS), one of the most delicate phases of matter, for the first time in a monolayer 2D semiconductor.

Extensive review of spin-gapless semiconductors: Next-generation spintronics candidates
An Australian has published an extensive review of spin-gapless semiconductors (SGSs), a new class of 'zero bandgap' materials which have fully spin polarised electrons and holes, and first proposed in 2008 by the review team's lead, Professor Xiaolin Wang (University of Wollongong).

2D molecular crystals modulating electronic properties of organic semiconductors
Recently, researchers report a controllable surface doping strategy utilizing 2D molecular crystals (2DMCs) as dopants to boost the mobility and to modulate the threshold voltage of OFETs.

Shedding new light on nanolasers using 2D semiconductors
Cun-Zheng Ning, a professor of electrical engineering in the Ira A.

The future of semiconductors is clear
Mobility is a key parameter for semiconductor performance and relates to how quickly and easily electrons can move inside a substance.

Semiconductors can behave like metals and even like superconductors
The crystal structure at the surface of semiconductor materials can make them behave like metals and even like superconductors, a joint Swansea/Rostock research team has shown.

Read More: Organic Semiconductors News and Organic Semiconductors Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to