TiO₂/WO₃ Bilayer as Electron Transport Layer for Efficient Planar Perovskite Solar Cell with Efficiency Exceeding 20%

Abstract

It is crucial to retard the carrier recombination and minimize the energy loss at the transparent electrode/electron transport layer (ETL)/perovskite absorber interfaces to improve the performance of the perovskite solar cells (PSCs). Here, a bilayered TiO2/WO3 film is designed as ETL by combining atomic layer deposition (ALD) technology and spin‐coating process. The ALD‐TiO2 underlayer fills the fluorine‐doped tin oxide (FTO) valleys and makes the surface smoother, which effectively avoids the shunt pathways between perovskite layer and FTO substrate and thereby suppresses electron–hole recombination at the interface. Moreover, the presence of hydrophilic TiO2 underlayer is helpful in forming a uniform and compact WO3 layer which is beneficial for extracting electron from perovskite to ETL. Meanwhile, the lower valance band minimum level of TiO2 relative to WO3 can efficiently enhance the hole‐blocking ability. By employing the optimized TiO2 (7 nm)/WO3 bilayer as ETL, the resulting cell exhibits an obviously enhanced power conversion efficiency of up to 20.14%, which is much better than the single WO3 or TiO2 ETL based device. This work is expected to provide a viable path to design ultrathin and compact ETL for efficient PSCs.

Colloidal SnO2‐Assisted CdS Electron Transport Layer Enables Efficient Electron Extraction for Planar Perovskite Solar Cells

“…Figure 4b shows the XRD patterns of the perovskite deposited on CdS and S-CdS ETLs. The peaks located at 14.14 o and 28.5 o can be attributed to (110) and (220) reflections of MAPbI 3 , respectively, [36] revealing the well-crystalline perovskite on both ETLs. The additional peak (2θ ¼ 12.64 o ) near the (110) peak is indexed to the (001) lattice plane for redundant PbI 2 , arising from the incomplete conversion of PbI 2 into MAPbI 3 , which has been widely reported in the literatures.…”

Sustained, photocatalytic CO2 reduction to CH4 in a continuous flow reactor by earth-abundant materials: Reduced titania-Cu2O Z-scheme heterostructures

“…5b, using Eq. S1 based on decay times (τ) and their amplitudes (A) [56]. The average emission life time (τavg), is generally a combination of fast decay component (τ1) and slow decay component (τ2), was calculated from Eq.…”

Robust Inorganic Hole Transport Materials for Organic and Perovskite Solar Cells: Insights into Materials Electronic Properties and Device Performance

“…[220] In fact, WO x can be used as both the ETL and the HTL due to their wide bandgap and energetics and high carrier mobility (20 cm 2 V À1 s 1 ). [221][222][223] For instance, when used as an ETL, WO x resulted in a higher J SC than TiO 2 counterpart in PSCs using MAPbI x Cl 1Àx as an absorber layer and Spiro-OMeTAD as the HTL. [224] The WO x ETL showed a nearly identical transmittance as that of TiO 2 but a higher conductivity.…”