University of Freiburg researchers have developed a monolithically integrated photo battery using organic materials that is capable of powering miniature devices. The photo battery achieves an unprecedented high discharge potential of 3.6 volts..

The team published the information about the technology in the journal Energy & Environmental Science.

The monolithically integrated photo battery made of organic materials achieves a discharge potential of 3.6 volts. Image Credit: Robin Wessling. Click this link for access to the study paper that at posting is not behind a paywall.

Networked intelligent devices and sensors can improve the energy efficiency of consumer products and buildings by monitoring their consumption in real time.

Miniature devices like these being developed under the concept of the Internet of Things require energy sources that are as compact as possible in order to function autonomously.

Monolithically integrated batteries that simultaneously generate, convert, and store energy in a single system could be used for this purpose.

Self powered devices wouldn’t need wired in power sources.

The team of scientists at the University of Freiburg’s Cluster of Excellence Living, Adaptive, and Energy-Autonomous Materials Systems (livMatS) developed the monolithically integrated photo battery consisting of an organic polymer-based battery and a multi-junction organic solar cell.

The battery, introduced by Rodrigo Delgado Andrés and Dr. Uli Würfel, University Freiburg, and Robin Wessling and Prof. Dr. Birgit Esser, University of Ulm, is the first monolithically integrated photo battery made of organic materials to achieve the discharge potential of 3.6 volts.

Combination of a multi-junction solar cell and a dual-ion battery

 The researchers developed a scalable method for the photo battery which allows them to manufacture organic solar cells out of five active layers.

Wessling explained, “The system achieves relatively high voltages of 4.2 volts with this solar cell.”

The team combined this multi-junction solar cell with a so-called dual-ion battery, which is capable of being charged at high currents, unlike the cathodes of conventional lithium batteries. With careful control of illumination intensity and discharge rates, a photo battery constructed in this way is capable of rapid charging in less than 15 minutes at discharge capacities of up to 22 milliampere hours per gram (mAh g-1).

In combination with the averaged discharge potential of 3.6 volts, the devices can provide an energy density of 69 milliwatt hours per gram (mWh g-1) and a power density of 95 milliwatts per gram (mW g-1).

“Our system thus lays the foundation for more in-depth research and further developments in the area of organic photo batteries,” said Wessling.


This is quite the tiny battery!! Paired up with the solar cell the ability to monitor will be much expanded. Still a very new technology we have little information, but 3.6 volts is way better than 1.5 or even 3.0 in series.

But the major appeal is going to be location access. Not needed to install power cabling is a huge advantage an great expander of location potential.


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