Passivation Mechanism Exploiting Surface Dipoles Affords High-Performance Perovskite Solar Cells

Abstract

The employment of 2D perovskites is a promising approach to tackling the stability and voltage issues inherent in perovskite solar cells. It remains unclear, however, whether other perovskites with different dimensionalities have the same effect on efficiency and stability. Here, we report the use of quasi-3D azetidinium lead iodide (AzPbI3) as a secondary layer on top of the primary 3D perovskite film that results in significant improvements in the photovoltaic parameters. Remarkably, the utilization of AzPbI3 leads to a new passivation mechanism due to the presence of surface dipoles resulting in a power conversion efficiency (PCE) of 22.4%. The open-circuit voltage obtained is as high as 1.18 V, which is among the highest reported to date for single junction perovskite solar cells, corresponding to a voltage deficit of 0.37 V for a band gap of 1.55 eV.

Tuning halide perovskite energy levels

“…When the perovskite surface is functionalized with dipoles, there are different factors which can affect the devices' PV parameters. The dipoles induce a change in energy level alignment, but at the same time, there is evidence that they can have a passivating effect 55 . Besides, the molecules are binding to defects on the perovskite surface, reducing in this way the trap states.…”

“…The V oc increase is instead consistent with an improvement in energy level alignment and with suppression of recombination. There is evidence that the latter could also be related to the presence of an electric field generated by the dipoles, which can push away the electrons from the interface 55 . It is also worth highlighting the consistency of this behaviour with the results from a previous work employing IPFC10 at the interface between perovskite and C60 in n-i-p PSCs 35 ,…”

Organic Tetrabutylammonium Cation Intercalation to Heal Inorganic CsPbI3 Perovskite

“…Furthermore, the TBAPbI 3 single crystal and thin film are quite stable (Supporting Information, Figure S13). With the TBAPbI 3 layer, the phase stability of thin films was also significantly enhanced (Supporting Information, Figure S14), probably because the formed 1D perovskite can work as terminal group as well [32–34] …”

Efficient Inverted Perovskite Solar Cells with Low Voltage Loss Achieved by a Pyridine‐Based Dopant‐Free Polymer Semiconductor

“…To reduce the defect formation, several techniques have been developed to increase the size of GBs, including compositional/additive engineering, processing methods optimization, and so on [13–17] . Alternatively, GB and surface passivation has demonstrated as an efficient and general approach to heal the detrimental defects to boost the device performance [18–26] . For example, Huang et al.…”