Perovskite solar cells (PSCs) are the next generation of photovoltaic technologies that use inorganic-organic hybrid perovskite of ABX3 type structures as light harvesting materials.
Most transparent electrodes for flexible PSCs are made of indium tin oxide (ITO). Although these ITO transparent electrodes have high transparency and conductivity (80% and 15Ω/m2, respectively), they have a number of problems including limited indium sources, high cost due to deposition techniques (sputtering, evaporation and pulsed laser deposition, etc.) and high mechanical brittleness.
Since transparent conductive films based on AgNWs show excellent performance such as high optical transmittance and low sheet resistance along with simple fabrication process and excellent mechanical flexibility, they have been deemed as the most promising alternative to ITO.
However, the transparent electrodes made of bare Ag nanowire networks have a rough surface and the gaps between silver nanowires cause serious parasitic lateral current flow, which leads the performance of devices to the dramatic failure.
Jon Sang Mo, a researcher at the Faculty of Applied Chemistry, has resolved problems with incorporating AgNW networks into PSCs such as smooth surface morphology, space filling and chemical stability, by employing solution-deposition of conductive ATO nanoparticles onto pre-existing AgNW networks at low temperatures.
The PET/AgNW/ATO composite transparent electrodes showed a transmission of 76–82 % in the visible region with an excellent sheet resistance of 18Ω/m2, similar to the commercial PET/ITO plastic substrates.
To build up flexible PSCs, he adopted the simple architecture, in which the CH3NH3PbI3 thin film was sandwiched between ZnO (as the electron-selective layer) and the carbon electrode (as the hole-selective layer) on the AgNW/ATO composite transparent electrodes.
Under AM 1.5 G and 100 mW/cm2 simulated sunlight illumination, the flexible PSCs based on AgNW/ATO composite transparent electrodes achieved PCEs of 5.07 %. JSC, VOC, and FF were 9.8mA/cm2, 835mV and 0.62, respectively.
The new fabrication technique on such a cheap transparent electrode could advance the roll-to-roll mass production of flexible low-cost PSCs.
You can find detailed information about this in his paper “Flexible perovskite solar cells based on AgNW/ATO composite transparent electrodes” presented to the SCI Journal “Synthetic Metals”).
© 2021 Kim Chaek University of Technology