Abstract
The performance of perovskite optoelectronic devices depends critically on the contact between the active layer and charge transport materials. To reveal the mechanism of barrier formation on perovskite surfaces, we studied Schottky junctions between various metals and a p-type perovskite CsSnBr3. By constructing slab models of the junction interface and aligning atomic core levels, the contacts between Au/CsSnBr3 and graphite/CsSnBr3 were found to be ohmic, but various other metals produced Schottky junctions with CsSnBr3. These calculation results, supported by x-ray photoelectron spectroscopy measurements, suggest that the barrier height of a metal/CsSnBr3 junction is a linear function of the metal’s electronegativity, rather than its work function. By introducing the concept of effective electronegativity for compounds, this trend was extended to a general rule that a suitable transport material should have an effective electronegativity to match that of the perovskite.
Highlights
Halide perovskites have captured enormous enthusiasm in materials research, because of their excellent optoelectronic properties1–4 and increasing applications in photodetectors,5,6 solar cells,7,8 and electroluminescent devices.9,10 In these devices, the conversion between light and charge carriers takes place in the bulk of the perovskite active layer, and the electrical current is collected or injected via the transport materials in contact with perovskite, where a minimal barrier is desirable to optimize the device performance
The classical guideline for aligning semiconductor interfacial energetics is the Schottky–Mott rule,11,12 which states that the surface barrier height Φ at a metal/semiconductor junction equals the difference between the metal’s Fermi level EF and the semiconductor’s band edge
Au has been employed as a contact material to extract photogenerated holes from perovskites,26,27 systematic investigations on perovskite junctions have remained scarce so far
Summary
Halide perovskites have captured enormous enthusiasm in materials research, because of their excellent optoelectronic properties1–4 and increasing applications in photodetectors,5,6 solar cells,7,8 and electroluminescent devices.9,10 In these devices, the conversion between light and charge carriers takes place in the bulk of the perovskite active layer, and the electrical current is collected or injected via the transport materials in contact with perovskite, where a minimal barrier is desirable to optimize the device performance. Published Online: 16 June 2020 Ruiying Long, Binghan Li and Qixi Mi The classical guideline for aligning semiconductor interfacial energetics is the Schottky–Mott rule,11,12 which states that the surface barrier height Φ at a metal/semiconductor junction equals the difference between the metal’s Fermi level EF and the semiconductor’s band edge.
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