Ajay K. Baranwal

100 °C Thermal Stability of Printable Perovskite Solar Cells Using Porous Carbon Counter Electrodes.

Many efforts have been made towards improving perovskite (PVK) solar cell stability, but their thermal stability, particularly at 85 °C (IEC 61646 climate chamber tests), remains a challenge. Outdoors, the installed solar cell temperature can reach up to 85 °C, especially in desert regions, providing sufficient motivation to study the effect of temperature stress at or above this temperature (e.g., 100 °C) to confirm the commercial viability of PVK solar cells for industrial companies. In this work, a three-layer printable HTM-free CH3 NH3 PbI3 PVK solar cell with a mesoporous carbon back contact and UV-curable sealant was fabricated and tested for thermal stability over 1500 h at 100 °C. Interestingly, the position of the UV-curing glue was found to drastically affect the device stability. The side-sealed cells show high PCE stability and represent a large step toward commercialization of next generation organic-inorganic lead halide PVK solar cells.

Lead-free perovskite solar cells using Sb and Bi-based A 3 B 2 X 9 and A 3 BX 6 crystals with normal and inverse cell structures

Research of CH3NH3PbI3 perovskite solar cells had significant attention as the candidate of new future energy. Due to the toxicity, however, lead (Pb) free photon harvesting layer should be discovered to replace the present CH3NH3PbI3 perovskite. In place of lead, we have tried antimony (Sb) and bismuth (Bi) with organic and metal monovalent cations (CH3NH3+, Ag+ and Cu+). Therefore, in this work, lead-free photo-absorber layers of (CH3NH3)3Bi2I9, (CH3NH3)3Sb2I9, (CH3NH3)3SbBiI9, Ag3BiI6, Ag3BiI3(SCN)3 and Cu3BiI6 were processed by solution deposition way to be solar cells. About the structure of solar cells, we have compared the normal (n-i-p: TiO2-perovskite-spiro OMeTAD) and inverted (p-i-n: NiO-perovskite-PCBM) structures. The normal (n-i-p)-structured solar cells performed better conversion efficiencies, basically. But, these environmental friendly photon absorber layers showed the uneven surface morphology with a particular grow pattern depend on the substrate (TiO2 or NiO). We have considered that the unevenness of surface morphology can deteriorate the photovoltaic performance and can hinder future prospect of these lead-free photon harvesting layers. However, we found new interesting finding about the progress of devices by the interface of NiO/Sb3+ and TiO2/Cu3BiI6, which should be addressed in the future study.

All-inorganic inverse perovskite solar cells using zinc oxide nanocolloids on spin coated perovskite layer

We confirmed the influence of ZnO nanoparticle size and residual water on performance of all inorganic perovskite solar cells. By decreasing the size of the ZnO nanoparticles, the short-circuit current density (Jsc) and open circuit photovoltage (Voc) values are increased and the conversion efficiency is improved. Although the Voc value is not affected by the influence of residual water in the solution for preparing the ZnO layer, the Jsc value drops greatly. As a result, it was found that it is important to use the oxide nanoparticles with a small particle diameter and to reduce the water content in the oxide forming material in order to manufacture a highly efficient all inorganic perovskite solar cells.