The Internet of Things comprises a billion smart wireless objects that share data in real-time via sensors and collaborate to achieve common goals, creating a new technology revolution. Although IoT devices typically use modest power (µW to mW), securing a reliable energy supply is a significant challenge. In addition to high maintenance and limited placement options, using wired or battery systems limits energy use. With the IoT ecosystem's exponential expansion, millions of batteries will need to be replaced regularly.[1]

The energy provided by most indoor lightbulbs has the potential to power small IoT devices and replace batteries. It is possible to design near-perpetual intelligent IoT devices with lifetimes of 10–20 years exploiting ambient light collected by Indoor Photovoltaic devices (IPVs) tailored explicitly for ambient light. The spectra of most interior illumination lamps, such as CFL or LED bulbs, range between 380 and 780 nm.[2] This spectral area supplies widely available, untapped energy. Dye-sensitized solar cells (DSC) are the best at capturing ambient light. PCEs up to 34%,[3] outperforming the established silicon technology and thin-film solar cells made from toxic materials. Fast charge separation in sensitizers, tuneable energy levels in copper complexes, and low recombination allow DSCs to sustain a high photovoltage near 1 V under ambient light.

We designed and implemented a photocapacitor architecture for ambient light harvesting, which powers wireless IoT devices. The photocapacitor has a DSC and a double-layer capacitor (EDLC). The EDLC supercapacitors can store intermittent energy with fast charge-discharge processes, high specific power, and long life cycles.[4][5] Organic conductive materials, such as Polyaniline (PANI) and Polypyrrole (PPy), have previously demonstrated excellent charge-storing properties as electrodes in symmetrical supercapacitors separated by a Nafion ion exchange membrane.[6][7] We have developed new highly stable electrodes with organic polycationic polymers known as polyviologens, which have previously demonstrated excellent capabilities for charge storage.[8] The novel polyviologen systems were deposited into poly 3,4-ethylenedioxythiophene (PEDOT) electrodeposited onto FTO substrates. PEDOT acts as a thin-porous layer to increase the polymer material's mass-loading and generate a pseudocapacitive response to delay capacitor discharge. To create a full photocapacitor, the supercapacitors based on polyviologens will be coupled to DSCs using copper complexes as hole transporter materials (HTM). This project intends to overcome the gap in energy supply availability during day-night cycles by storing surplus charges converted by the DSC in polyviologen supercapacitors.