Unconventional Route to Oxygen‐Vacancy‐Enabled Highly Efficient Electron Extraction and Transport in Perovskite Solar Cells

Abstract

The ability to effectively transfer photoexcited electrons and holes is an important endeavor towardachieving high-efficiency solar energy conversion. Now,asimple yet robust acid-treatment strategy is used to judiciously create an amorphous TiO 2 buffer layer intimately situated on the anatase TiO 2 surface as an electron-transport layer (ETL) for efficient electron transport. The facile acid treatment is capable of weakening the bonding of zigzag octahedral chains in anatase TiO 2 ,therebyshortening staggered octahedron chains to form an amorphous buffer layer on the anatase TiO 2 surface.S uch amorphous TiO 2-coated ETL possesses an increased electron density owingt ot he presence of oxygen vacancies,l eading to efficient electron transfer from perovskite to TiO 2 .C ompared to pristine TiO 2-based devices,the perovskite solar cells (PSCs) with acid-treated TiO 2 ETL exhibit an enhanced short-circuit current and power conversion efficiency.

In Situ Surface Fluorination of TiO2 Nanocrystals Reinforces Interface Binding of Perovskite Layer for Highly Efficient Solar Cells with Dramatically Enhanced Ultraviolet‐Light Stability

“…[6] On the other hand, F-doping imposes negligible influence on the UV-vis optical absorption of TiO 2 , while the optical bandgap of TiO 2 estimated from the diffuse reflectance spectra increases slightly from 3.13 eV (the pristine TiO 2 ) to 3.17 eV (50%-F-TiO 2 ) after F-doping (Figure S5, Supporting Information), consistent with the passivated surface oxygen vacancies after F doping. [12] The electron mobility of TiO 2 film is measured by the space charge limited current (SCLC) method with a sandwiched structure of indium tin oxide (ITO)/Ag/TiO 2 /Ag. [13] The corresponding I-V curves for the electron-only devices based on different TiO 2 films are illustrated in Figure 1h, from which the electron mobility (µ e ) of the pristine TiO 2 , 4%-F-TiO 2 , 12%-F-TiO 2 , and 50%-F-TiO 2 films are calculated to be 0.77 × 10 −4 , 1.21 × 10 −4 , 1.92 × 10 −4 , and 5.29 × 10 −4 cm 2 V −1 s −1 , respectively (see Figure S6 and Table S4 in the Supporting Information).…”

Oxygen-deficient perovskites for oxygen evolution reaction in alkaline media: a review

“…For instance, Mn-doped Bi 0.5 Na 0.5 TiO 3 EPR analysis found a gparameter of 2.0015. Numerous findings of g-parameters approaching 2.00 for oxygen-deficient perovskites and transition metal oxides (TMOs) co-confirmed with other oxygen vacancy characterization techniques have been reported in recent years [84][85][86]. Acquiring information pertaining to molecular vibrations and rotations via Raman spectroscopy is another tool continued to be adopted for identifying oxygendeficient materials and perovskites in general [87][88][89][90].…”

“…Moreover, anionic vacancies tend to modify band structures-as can be seen from DFT band structure calculations of oxygen-deficient materials. Such band structure changes can lead to potential alternate paths for excited electron generation and recombination-which occurs from lightdirected electron excitation during photoluminescence (PL) readings [85,91]. Peak position and intensity of the PL spectra show easily identifiable changes upon such electronic modulations from oxygen vacancies [92].…”

Organolead halide perovskites beyond solar cells: self-powered devices and the associated progress and challenges

“…46 ETLs not only influence the electron transfer and collection but also behave as the hole blocking layer to suppress the electron-hole recombination at the interface. 47,48 Significant attention was paid to ZnO as electron transport material (ETL) in the early research works reporting OLHP based self-powered PDs. Specifically, morphological tuning of ZnO material was used for performance optimization of the OLHP PDs.…”