The Influence of the Thickness of Compact TiO2 Electron Transport Layer on the Performance of Planar CH3NH3PbI3 Perovskite Solar Cells

Abstract

In recent years, lead halide perovskites have attracted considerable attention from the scientific community due to their exceptional properties and fast-growing enhancement for solar energy harvesting efficiency. One of the fundamental aspects of the architecture of perovskite-based solar cells (PSCs) is the electron transport layer (ETL), which also acts as a barrier for holes. In this work, the influence of compact TiO2 ETL on the performance of planar heterojunction solar cells based on CH3NH3PbI3 perovskite was investigated. ETLs were deposited on fluorine-doped tin oxide (FTO) substrates from a titanium diisopropoxide bis(acetylacetonate) precursor solution using the spin-coating method with changing precursor concentration and centrifugation speed. It was found that the thickness and continuity of ETLs, investigated between 0 and 124 nm, strongly affect the photovoltaic performance of PSCs, in particular short-circuit current density (JSC). Optical and topographic properties of the compact TiO2 layers were investigated as well.

Crack-Free and Thickness-Controllable Deposition of TiO2–rGO Thin Films for Solar Harnessing Devices

“…Mesoporous TiO 2 thin films are widely utilized as electron transport layers in solar harvesting devices, such as dye-sensitized solar cells [1,2], perovskite solar cells [3,4], and photoelectrochemical cells [5]. However, the efficiency of electron transport in these TiO 2 thin films is hindered because of charge trapping, recombination, and grain boundary scattering effects [6,7].…”

Photoelectric Properties of Planar and Mesoporous Structured Perovskite Solar Cells

“…An ETL transports photoinduced electrons away from the perovskite, and at the same time, it serves as a blocking layer preventing direct contact between the holes and fluorine-doped tin oxide (FTO) [24,25]. Therefore, TiO 2 layers should be uniform, pinhole-free, and should completely cover the surface of FTO [26]. The optimal thickness of crystalline TiO 2 depends on the deposition technique and post-treatment of the layers.…”

“…The optimal thickness of crystalline TiO 2 depends on the deposition technique and post-treatment of the layers. In the case of planar PSCs, the thickness of an ETL is in the range of 20-30 nm [26][27][28]. The deposition of a mesoporous (mp-TiO 2 ) layer on crystalline titanium dioxide provides a reduced carrier transport length and increased interfacial contact area, thereby facilitating efficient charge carrier collection and yielding the highest reported PCE values [29].…”

“…The deposition of a mesoporous (mp-TiO 2 ) layer on crystalline titanium dioxide provides a reduced carrier transport length and increased interfacial contact area, thereby facilitating efficient charge carrier collection and yielding the highest reported PCE values [29]. It has been shown that the structural properties of the mp-TiO 2 layer, such as particle size, thickness, and porosity, have a significant influence not only on the performance of PSCs but also on the layer's photoelectric properties [13,26,[30][31][32]. The transient photovoltage (TPV) measurements showed that the TPV decay strongly depends on the porosity of TiO 2 film, and there is a significant correlation between the TPV decay characteristics and the performance of the perovskite solar cells [13].…”

Recent Advances in Modeling of Perovskite Solar Cells Using SCAPS-1D: Effect of Absorber and ETM Thickness

“…Many studies have demonstrated that the PCE of PSCs is generally dependent on thickness of the perovskite absorber [12][13][14][15]. Thickness of electron transport layers are also crucial for better efficiencies [13][14][15][16][17].…”