Abstract
The photocurrent generation in photovoltaics relies essentially on the interface of p-n junction or Schottky barrier with the photoelectric efficiency constrained by the Shockley-Queisser limit. The recent progress has shown a promising route to surpass this limit via the bulk photovoltaic effect for crystals without inversion symmetry. Here we report the bulk photovoltaic effect in two-dimensional ferroelectric CuInP2S6 with enhanced photocurrent density by two orders of magnitude higher than conventional bulk ferroelectric perovskite oxides. The bulk photovoltaic effect is inherently associated to the room-temperature polar ordering in two-dimensional CuInP2S6. We also demonstrate a crossover from two-dimensional to three-dimensional bulk photovoltaic effect with the observation of a dramatic decrease in photocurrent density when the thickness of the two-dimensional material exceeds the free path length at around 40 nm. This work spotlights the potential application of ultrathin two-dimensional ferroelectric materials for the third-generation photovoltaic cells.
Highlights
The photocurrent generation in photovoltaics relies essentially on the interface of p-n junction or Schottky barrier with the photoelectric efficiency constrained by the ShockleyQueisser limit
The low-dimensional materials such as CuInP2S6, α-In2Se3, and MoTe2 with layered van der Waals structure without inversion symmetry have been suggested for high-efficiency photocurrent collection via BPVE17–23
We demonstrate a crossover from 2D to 3D photovoltaics when the thickness of the CIPS exceeds the free path length (l0) of photocarriers, beyond which the photocurrent reduces to the dark condition level even with inversion asymmetry
Summary
The photocurrent generation in photovoltaics relies essentially on the interface of p-n junction or Schottky barrier with the photoelectric efficiency constrained by the ShockleyQueisser limit. 1234567890():,; The bulk photovoltaic effect (BPVE), a kind of nonlinear optical process that converts light into electricity in solids, has a potential advantage in a solar cell with an efficiency that exceeds the fundamental Schockley–Queisser (S–Q) limit[1,2,3,4,5,6,7] This effect is only valid in crystals with broken inversion symmetry, which can lead to significant electronic polarization[8,9,10] that plays a similar role as the p–n junction and Schottky barrier in photovoltaics. We demonstrate a crossover from 2D to 3D photovoltaics when the thickness of the CIPS exceeds the free path length (l0) of photocarriers, beyond which the photocurrent reduces to the dark condition level even with inversion asymmetry These results highlight the potential of developing nextgeneration solar cells with ultrathin 2D materials
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