High efficiency perovskite quantum dot solar cells with charge separating heterostructure

Abstract

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.

Secondary Ion Mass Spectrometry (SIMS) for Chemical Characterization of Metal Halide Perovskites

“…(d-f) Reproduced with permission. [78] Copyright 2019, Springer Nature. g-i) ToF-SIMS 3D tomography of mixed Pb/Sn perovskite, Pb-based perovskite, graded Pb/Sn perovskite, respectively.…”

“…[77] Zhao et al developed a perovskite QDs device with GHJ within the perovskite layer. [78] Three representative films-film-1 with pure CsPbI 3 QDs, film-2 with CsPbI 3 QDs on top of Cs 0.25 FA 0.75 PbI 3 QDs, and film-3 with Cs 0.25 FA 0.75 PbI 3 QDs on top of CsPbI 3 QDs-were investigated by ToF-SIMS to study the compositional change. ToF-SIMS depth profile shows uniform Cs, Pb, and I distribution in film-1 (Figure 10d).…”

“…These results indicate that a GHJ was formed in film-2 and film-3 by controlling chemical composition, which facilitates charge separation and enhance the performance of perovskite QDs solar cells. [78] The GHJ perovskite stacking structure was also developed to improve the performance of carbon electrodebased hole transport layer free perovskite solar cells, [79] where a MAPbI x Br 3−x layer was grown on the MAPbI 3 layer to form a MAPbI 3 -MAPbI x Br 3−x GHJ structure. ToF-SIMS depth profiles show that the Br is mainly distributed at the top of the perovskite film with a depth of ≈75 nm, confirming the GHJ structure in the perovskite film.…”

High‐Efficiency Perovskite Quantum Dot Hybrid Nonfullerene Organic Solar Cells with Near‐Zero Driving Force

“…[ 26,27 ] Among them, CsPbI 3 is widely used due to its optimal bandgap ( E g ≈ 1.73 eV), high dielectric constant, large absorption attenuation coefficient, strong fluorescence, and long‐range electron transport. [ 28–31 ] CsPbI 3 perovskite quantum dots (PQDs) were used for perovskite solar cells, [ 32–36 ] light‐emitting diodes, [ 37–39 ] and even fullerene‐based OSCs. [ 40 ]…”

Optimizing the Atomic Layer Deposition of Alumina on Perovskite Nanocrystal Films by Using O2 As a Molecular Probe

“…Of particular note, metal halide perovskite nanocrystals (NCs) can be obtained through colloidal chemistry; their electronic structure and concomitant optical properties are tailored through synthetic control of size, shape, and composition . These properties have led to the use of perovskite NCs as photoactive components in technologies such as light‐emitting diodes, solar cells, and photocatalysts …”