Vacuum-Deposited Microcavity Perovskite Photovoltaic Devices
The interaction between semiconductor materials and electromagnetic fields resonating in microcavities or the light-matter coupling is of both fundamental and practical significance for improving the performance of various photonic technologies. The demonstration of light-matter coupling effects in the emerging perovskite-based optoelectronic devices via optical pumping and electrical readout (e.g., photovoltaics) and vice versa (e.g., light-emitting diodes), however, is still scarce. Here, we demonstrate the microcavity formation in vacuum-deposited methylammonium lead iodide (CH3NH3PbI3, MAPI) p-i-n photovoltaic devices fabricated between two reflecting silver electrodes. We tune the posi…
Electrothermal Feedback and Absorption-Induced Open-Circuit-Voltage Turnover in Solar Cells
A solar panel gets hot as it works up on the roof, yet photoinduced self-heating is often ignored when characterizing lab-sized samples. The authors present their understanding of the turnover effect in measurements of open-circuit voltage versus light intensity (Suns-${V}_{O\phantom{\rule{0}{0ex}}C}$ curves), which is identified as a unique feature of all semiconductor-based solar cells. This effect is explained in terms of electrothermal feedback arising when the incident irradiation heats up the device. The authors' model fully explains the experimental data, and allows one to determine key device parameters such as the ideality factor and the band gap from a single measurement.
High voltage vacuum-deposited CH3NH3PbI3-CH3NH3PbI3 tandem solar cells
The recent success of perovskite solar cells is based on two solid pillars: the rapid progress of their power conversion efficiency and their flexibility in terms of optoelectrical properties and processing methods. That versatility makes these devices ideal candidates for multi-junction photovoltaics. We report an optically optimized double junction CH3NH3PbI3–CH3NH3PbI3 tandem solar cell where the matched short-circuit current is maximized while parasitic absorption is minimized. The use of an additive vacuum-deposition protocol allows us to reproduce calculated stack designs, which comprise several charge selective materials that ensure appropriate band alignment and charge recombination…