Study of Degradation in Electrical Conductivity of Carrier Transport Materials for Perovskite Solar Cells

• Jacob Baker, Computer Engineering, University of Delaware

• Steven Hegedus, Electrical and Computer Engineering, University of Delaware

Over the last decade, perovskite solar cells have emerged as a major focus of research in the field. This technology proves to be exciting as a result of its low cost and high efficiency compared to existing solar cell technologies. Carrier transport layers in perovskite solar cells play an important role in extracting the electricity out of solar cells. They create a potential difference across the perovskite light absorber layer to allow current transport. Materials for carrier transport layers should be conductive enough to transport the photogenerated current without any loss, while also containing the properties required to produce a potential difference. The conductivity of these materials can degrade under different environmental conditions, so investigating the rate of change is essential for determining how to preserve them effectively. In this work, I study the degradation and conductivity of four different carrier transport materials, which are tin(IV) oxide (SnO2), nickel oxide (NiO), buckminsterfullerene (C60) and copper phthalocyanine (CuPC), under two conditions: exposure to air and storage in a nitrogen-filled glove box. I used thermal evaporation and sputtering to deposit the carrier transport materials on glass and put a metal contact on to measure conductivity. I measured the conductivity of the materials over the course of two weeks. The results showed that depending on the material, the environment they are kept in has a unique impact on their conductivity over time. NiO is more stable in a nitrogen filled glove box, while C60 and CuPC degrade in both environments. For SnO2, the conductivity initially increases after the first day, and degrades more slowly in the air than in the glovebox.