Broadband Light Absorption and Efficient Charge Separation Using a Light Scattering Layer with Mixed Cavities for High‐Performance Perovskite Photovoltaic Cells with Stability

Abstract

CH NH PbI is one of the promising light sensitizers for perovskite photovoltaic cells, but a thick layer is required to enhance light absorption in the long-wavelength regime ranging from PbI absorption edge (500 nm) to its optical band-gap edge (780 nm) in visible light. Meanwhile, the thick perovskite layer suppresses visible-light absorption in the short wavelengths below 500 nm and charge extraction capability of electron-hole pairs produced upon light absorption. Herein, we find that a new light scattering layer with the mixed cavities of sizes in 100 and 200 nm between transparent fluorine-doped tin oxide and mesoporous titanium dioxide electron transport layer enables full absorption of short-wavelength photons (λ < 500 nm) to the perovskite along with enhanced absorption of long-wavelength photons (500 nm < λ < 780 nm). Moreover, the light-driven electric field is proven to allow efficient charge extraction upon light absorption, thereby leading to the increased photocurrent density as well as the fill factor prompted by the slow recombination rate. Additionally, the photocurrent density of the cell with a light scattering layer of mixed cavities is stabilized due to suppressed charge accumulation. Consequently, this work provides a new route to realize broadband light harvesting of visible light for high-performance perovskite photovoltaic cells.

On the Morphology of Nanostructured TiO2 for Energy Applications: The Shape of the Ubiquitous Nanomaterial

“…So, novel morphologies of the mesoporous titania scaffolds were poorly investigated for their light diffusive properties, even though 3D flower-shaped [ 55 , 56 ] and hollow sphere [ 57 ] nanostructures were demonstrated to improve the light harvesting efficiency by several percent in the low wavelength region. On the other hand, many studies were devoted to the texture of the interface between the TiO 2 layer and the transparent conductive oxide in order to enhance the LT effect and accordingly improve the photocurrent: several papers report on the realization of hemispherical voids or titania structures on well-defined patterns [ 58 , 59 , 60 , 61 , 62 , 63 , 64 ]. These photonic structures maximize (see Figure 4 ) the long wavelength light absorption inside the cell and consequently allow higher photocurrent generation, yielding up to 13% improved overall conversion efficiencies.…”

Mesoporous Titanium Dioxide: Synthesis and Applications in Photocatalysis, Energy and Biology

“…Although mesoporous TiO 2 photocatalysts have been widely used, certain disadvantages, for example low photonutilization efficiency and poor absorption of visible light due to large band gap of TiO 2 (3–3.2 eV) have also limited their application. Therefore, a large amount of efforts has been directed to the modification of the material with the purpose of improving the photocatalytic effect and activity of mesoporous TiO 2 photocatalysts [ 48 , 49 , 50 , 51 , 52 ]. Among them, doping is one of the most promising ways for enhancing the performance of mesoporous TiO 2 .…”

Strain-Induced Metallization and Defect Suppression at Zipper-like Interdigitated Atomically Thin Interfaces Enabling High-Efficiency Halide Perovskite Solar Cells

“…We performed the EIS measurements for the PSCs with different ETL, as shown in the resulting Nyquist plots together with the equivalent circuit used for fitting (Figure 5a). The two semicircles are observed in the EIS spectra, while the first semicircle in the high-frequency range is attributed to the charge-transfer resistance at the ETL/perovskite and perovskite/HTL interfaces 45,46 and the second semicircle in the lowfrequency range is ascribed to the charge transfer within the TiO 2 layer. In the equivalent circuit, R s corresponds to the series resistance of the cell, which is determined from the highfrequency intercept of the left semicircle with the x-axis, and R TiO 2 and CPE TiO 2 refer to the charge transfer resistance and the CPE of the TiO 2 layer, respectively.…”