Charge Transport Layer-Dependent Electronic Band Bending in Perovskite Solar Cells and Its Correlation to Light-Induced Device Degradation

Abstract

Perovskite solar cells (PSCs) have shown remarkably improved power-conversion efficiency of around 25%. However, their working principle remains arguable and the stability issue has not been solved yet. In this report, we revealed that the working mechanism of PSCs is explained by a dominant p-n junction occurring at the different interface depending on electron transport layer, and charges are accumulated at the corresponding dominant junction initiating device degradation. Locations of a dominant p-n junction, the electric field, and carrier-density distribution with respect to electron-transport layers in the PCS devices were investigated by using the electron-beam-induced current measurement and Kelvin probe force microscopy. The amount of accumulated charges in the devices was analyzed using the chargeextraction method and the degradation process of devices was confirmed by SEM measurements. From these observations, we identified that the dominant p-n junction appears at the interface where the degree of band bending is higher compared to the other interface, and charges are accumulated at the corresponding junction where the device degradation is initiated, which suggests that there exists a strong correlation between PSC working principle and device degradation. We highlight that an ideal p-i-n PSC that can minimize the degree of band bending should be designed for ensuring long-term stability, via using proper selective contacts

Interpenetrating interfaces for efficient perovskite solar cells with high operational stability and mechanical robustness

“…The related topological and phase atomic force microscopy (AFM) images are shown in Supplementary Fig. 7 , demonstrating CPD results are independent of the surface topography 32 , 33 . The slope of the CPD profile suggests the existence of a p–n junction.…”

Insight into the Origins of Figures of Merit and Design Strategies for Organic/Inorganic Lead‐Halide Perovskite Solar Cells

“…[196b] When C 60 is substituted with TiO 2 , the degradation is depressed. [204] However, to cater to PSC commercialization, a number of thoughtful strategies should be developed for long-term operation stability based on the nature of organic/inorganic perovskites. Thus, several schemes have been shown to be competent and feasible as follows.…”

Photocorrosion at Irradiated Perovskite/Electrolyte Interfaces

“…Degradation of perovskites is generally considered to be a surface- or interface-initiated process that propagates toward the bulk material. 13 , 14 So far, the composition and morphology of the perovskite layer (grain boundaries), 15 choice of device constituents (charge extraction, electrode, and encapsulation layers) 16 and the passivation of various interfacial defects were scrutinized in this regard. 17 Charge extraction layer/perovskite interfaces also influence the corrosion pathways.…”

“… 17 Charge extraction layer/perovskite interfaces also influence the corrosion pathways. 14 , 18 UV light activated surface trap states of TiO 2 , 19 the surface hydroxyl groups of ZnO, 20 or the interaction with the dopants from the organic hole-extraction layers are all relevant examples. 21 The effect of these factors on the stability and performance of PC/PEC systems is yet to be understood, not even mentioning the role of liquid electrolyte present.…”