Quantum mechanics

Polymer solar cell

Ecology

Biology

Materials science

Layer (electronics)

Perovskite (structure)

Semiconductor

Inorganic chemistry

Photoactive layer

Quantum well

Laser

Physics

Nanotechnology

Optics

Quantum heterostructure

Thin film

Solar cell

Charge (physics)

Heterojunction

Crystallography

Chemistry

Quantum dot

Photovoltaics

Optoelectronics

Photovoltaic system

Halide

Nature Communications

Metal halide perovskite semiconductors possess outstanding characteristics for optoelectronic applications including but not limited to photovoltaics. Low-dimensional and nanostructured motifs impart added functionality which can be exploited further. Moreover, wider cation composition tunability and tunable surface ligand properties of colloidal quantum dot (QD) perovskites now enable unprecedented device architectures which differ from thin-film perovskites fabricated from solvated molecular precursors. Here, using layer-by-layer deposition of perovskite QDs, we demonstrate solar cells with abrupt compositional changes throughout the perovskite film. We utilize this ability to abruptly control composition to create an internal heterojunction that facilitates charge separation at the internal interface leading to improved photocarrier harvesting. We show how the photovoltaic performance depends upon the heterojunction position, as well as the composition of each component, and we describe an architecture that greatly improves the performance of perovskite QD photovoltaics.

High efficiency perovskite quantum dot solar cells with charge separating heterostructure