German researchers have increased the efficiency of an inverted perovskite solar cell from 15.9% to 20.1% using a mixed solvent vapor annealing method based on ethylenediamine (EDA).
“Our work shows how simple passivation can improve the performance and operational stability of a perovskite solar cell,” researcher Azhar Fakharuddin said. pv magazine.
EDA has been used in previous research projects to suppress various perovskite defect states, the scientists said.
“However, it remains unclear how EDA affects the morphology, passivation of defects, and optoelectronic properties of perovskite films,” they said.
They applied their EDA passivation technique with solvent vapor annealing followed by annealing at 90 C for 30 min to a film based on lead halide perovskite type. methylammonium lead iodide (MAPbI3). They claimed to be able to achieve improved crystallinity and a densely packed film morphology with larger grains than the non-passivated reference film.
They annealed the film in a vacuum chamber after spin coating and then placed it in a controlled EDA vapor environment with a concentration of 0.06 wt%. EDA interacted with the perovskite surfaces and led to the rearrangement of the surface properties.
“The 0.06% EDA passivated films also have a lower square-plane roughness of 13.7 nm than the pristine perovskite films,” the researchers said.
They used the film in a perovskite clock a pin structure and tested its performance under normal lighting conditions. The power conversion efficiency of the device is 20.1%, breakdown voltage 106 mV, short-circuit current 24.0 mA/cm2 and duty factor 79.9%. In comparison, the reference device without EDA treatment achieved 15.9% efficiency, 0.99 V breakdown voltage, 20.4 mA/cm2 short-circuit current, and 73.5% fill factor.
“The increase in open-circuit voltage and fill factor suggests suppressed non-radiative recombination and efficient charge removal in EDA-modified perovskite films,” the researchers said. “Inhibition of nonradiative recombination in EDA passivation is further evidenced by transient photocurrent (TPC) and light intensity-dependent JV measurements.”
The German research team determined that the EDA-modified cell was able to retain 88% of its original efficiency after 850 hours, while the efficiency of the reference cell dropped by 66% within 500 hours. They introduced cellular technology”Ethylenediamine vapor assisted surface passivation of perovskite films for efficient inverted solar cells”, which was published recently RRL sun.