Titanium Nanopillar Arrays Functioning as Electron Transporting Layers for Efficient, Anti‐Aging Perovskite Solar Cells

Abstract

Electron transporting layers (ETLs), required to be optically transparent in perovskite solar cells (PSCs) having regular structures, possess a determinant effect on electron extraction and collection. Metal oxides (e.g., TiO2) have overwhelmingly served as ETLs, but usually have low electron mobility (μe < 10−2 cm2 V−1 s−1) not favorable for photovoltaic conversion. Here, metal oxides are replaced with metals (e.g., Ti with μe ≈ 294 cm2 V−1 s−1) that are sculptured via glancing angle deposition to be a close‐packed nanopillar array (NaPA), which vertically protrudes on a transparent electrode to obtain sufficient optical transmission for light harvesting in perovskite. Ti NaPAs, whose rough surfaces are passivated with 5 nm thick TiO2 (i.e., Ti NaPAs@TiO2) to suppress exciton recombination, lead to the champion power conversion efficiency (PCE) of 18.89% that is superior to that of MAPbI3 PSCs without Ti NaPAs@TiO2 or containing TiO2 NaPAs@TiO2, owing to high surface wettability, high μe, and relatively low work function of Ti. Furthermore, Ti NaPAs@TiO2 effectively prevents the decomposition of MAPbI3 to achieve long‐term shelf stability whereby 50‐day aging only causes 15% PCE degradation. This work paves the way toward widening the material spectrum, from semiconductors to metals, to generate a diverse range of ETLs for producing efficient optoelectronic devices with long‐term shelf stability.

Energy Harvesting Materials and Structures for Smart Textile Applications: Recent Progress and Path Forward

“…Their long-term stability also improved without the need for encapsulation. Another study reported that decorating a transparent electrode with a close-packed titanium nanopillar array ( Figure 2 a) passivated with a 5 nm thick titanium dioxide (TiO 2 ) layer produced an electron-transporting layer with improved power conversion and long-term stability [ 33 ]. Perovskites have also shown great potential for the production of tandem structures with silicon and CICG [ 28 ].…”

“…For instance, according to the researchers' calculations, the amount of lead emission into the air, water, and ground associated with coal electricity production is at least as high as the amount of lead that would be contained in lead halide perovskite photovoltaic cells giving the same energy output. [33] with permission from Wiley); (b) ternary polymer used as active layer in organic photovoltaic cells (reproduced from [36] with permission from Wiley); (c) porosity and morphology of PVDF-HFP/PEO microporous membrane used in gel-like dye-sensitized solar cells (reproduced from [37] with permission from Elsevier).…”

“…They can also withstand the deformations associated with a use in a garment. Another major advantage is that polymer photovoltaic cells can [33] with permission from Wiley); (b) ternary polymer used as active layer in organic photovoltaic cells (reproduced from [36] with permission from Wiley); (c) porosity and morphology of PVDF-HFP/PEO microporous membrane used in gel-like dye-sensitized solar cells (reproduced from [37] with permission from Elsevier).…”

“…Figure 2. Examples of recent developments toward photovoltaic energy harvesting materials and structures for textile application: (a) different geometries of titanium nanopillars used as electron transporting layer in inorganic flexible solar cells (reproduced from[33] with permission from Wiley); (b) ternary polymer used as active layer in organic photovoltaic cells (reproduced from[36] with permission from Wiley); (c) porosity and morphology of PVDF-HFP/PEO microporous membrane used in gel-like dye-sensitized solar cells (reproduced from[37] with permission from Elsevier).…”

Sensitive, High‐Speed, and Broadband Perovskite Photodetectors with Built‐In TiO2 Metalenses

“…Importantly, the meta-TiO 2 exhibited a low contact angle (CA) of 14.89° (inset in Figure 3b) to facilitate the solution casting of the perovskite layer, resulting in the complete infiltration of Cs x M into the intervals of the meta-TiO 2 to form the intimate Cs x M/TiO 2 contacts (Figure 3b). [42] The current density-voltage (J-V) plots of the Cs x M photodetectors are shown in Figure 3c. The meta-TiO 2 -PD displayed a remarked enhancement in the optoelectronic properties compared to the meso-TiO 2 -PD and bl-TiO 2 -PD (Figure 3e).…”