Science News : 2021 ACS Energy Lett. PCE 22.26% Perovskite Solar Cells

　　ACS Energy Letters (IF 19.05) journal recently published research by Nam-Gyu Park et al. They would like to understand the impact of the chemical bonding nature of the post-processing materials using pyridinium iodide (PyI) with delocalized π electrons and piperidinium iodide (PpI) without a π bond on photovoltaic performance of perovskite solar cells.

　　The author uses a solar simulator and collects external quantum efficiency (EQE) spectra through a PV measuring instrument. The experimental results show that when the PyI concentration increases from 0 to 40 mM, the power conversion efficiency (PCE) gradually increases from 20.13% to 22.26%, but PCE is relatively optimized when the PpI concentration of 5 mM is relatively low. In addition, it was found that the formation of a PyI layer at the perovskite/HTL interface by PyI treatment is beneficial to hole extraction even when the interlayer thickness is increased. On the other hand, the insulation 1-D PpPbI₃ formed by PpI treatment will block charge separation, especially at high concentrations.

　　Therefore, a conclusion can be drawn that each material needs a different thickness to achieve decent photovoltaic parameters. Also, interface engineering is important to improve the charge transfer and reduce the interface defects of non-radiative recombination.