Underachieving solar cells get an organic upgrade
© WLADIMIR BULGAR/SCIENCE PHOTO LIBRARY/Getty
Low-cost alternatives to silicon solar cells can attain high efficiencies by simply tweaking their surface chemistry.
Researchers from Peking University have investigated an electronic problem that hinders the light-harvesting performance of perovskites — materials such as lead halides that can be printed, much like ink, onto solar devices.
When perovskites are sandwiched between electrodes in a thin-film solar cell, interfacial defects and impurities can prevent photogenerated charge carriers from contributing to the device’s power output. To control this effect, the researchers coated perovskite thin films with guanidinium, a natural nitrogen-rich ion. Electrical measurements showed that this overlay boosted the maximum solar cell voltage compared to uncoated perovskites.
Surface characterization measurements suggest the organic coating reduces the number of defects and alters the perovskite’s electronic structure to push photogenerated charges away from interfacial regions.
- Science 360, 1442–1446 (2018). doi: 10.1126/science.aap9282