Doping in Semiconductor Oxides‐Based Electron Transport Materials for Perovskite Solar Cells Application

Abstract

From the perspective of the device structure of perovskite solar cells (PSCs), the electron transport layer is one of the essential components and plays a significant role in suppressing carrier recombination. Furthermore, its decisiveness is related to the quality of perovskite film, the rapid interface carrier extraction, and the bandgap alignment. However, the deficiency of the semiconductor oxides based electron transport materials, especially for most studied TiO2, is that their carrier mobility is one to three orders of magnitude lower than the most commonly used hole transport materials, leading to an imbalanced carrier flux and unpredicted hysteresis. Doping new ions are the most effective ways to improve electron mobility and tune the bandgap, while the fundamental mechanism of doping in the majority of cases are still lacking. Herein, the doping effect on semiconductor oxides is reviewed and emphasized by classifying the doping ions according to the critical factors of lattice optimization, a carrier transporting improvement, and interface modification. This review is the first systematic summary of the ion doping characteristics in oxide electron transport layers of PSCs. Finally, the implementation of doping ions in electron transport materials is briefly discussed for further enhancing the photovoltaic performance of PSCs.

Interfacial carrier transport properties of a gallium nitride epilayer/quantum dot hybrid structure

“…3 However, TiO 2 has several inherent drawbacks typically including low electron mobility, high defect state density and poor chemical stability, which might result in charge accumulation at interface, and thus imbalanced electron/hole ux and unpredicted current-voltage hysteresis. [4][5][6] For QDSCs, studies on other novel ETLs are still lacking. Exploring novel ETLs as potential alternatives which enable suitable energy level alignment, rapid interface carrier extraction and good chemical stability for QDSCs is urgently expected.…”

Alkali Metal Chloride‐Doped Water‐Based TiO2 for Efficient and Stable Planar Perovskite Photovoltaics Exceeding 23% Efficiency

“…[ 21 ] Metal doping has been demonstrated to be an effective and facile solution to improve the electrical properties of ETL. [ 22–29 ] Especially, alkali metal salts doping has been investigated by virtue of their easy availability and incorporation. [ 23–26,32–35 ] For instance, the role of LiTFSI doping in mesoporous TiO 2 has been studied and found to improve the charge extraction ability, [ 24,25 ] yet the moisture absorption of LiTFSI has a potential impact on device stability.…”

“…[6][7][8] PSCs with an n-i-p configuration are usually composed of a transparent conductive electrode, an electron transport layer (ETL), a perovskite light absorption Especially, alkali metal salts doping has been investigated by virtue of their easy availability and incorporation. [23][24][25][26][32][33][34][35] For instance, the role of LiTFSI doping in mesoporous TiO 2 has been studied and found to improve the charge extraction ability, [24,25] yet the moisture absorption of LiTFSI has a potential impact on device stability. Sodium salts, including NaCl and Na 2 S, were also doped into high-temperature TiO 2 , and proven to suppress oxygen vacancies-induced nonradiative recombination.…”

“…[21] Metal doping has been demonstrated to be an effective and facile solution to improve the electrical properties of ETL. [22][23][24][25][26][27][28][29] TiO 2 is one of the most broadly employed electron transport materials in n-i-p structure perovskite solar cells (PSCs). Low-temperature non-hydrolyzed sol-gel method is developed to prepare TiO 2 in order to simplify the fabrication process and match with the planar structure PSCs.…”

Fast Light-Cured TiO2 Layers for Low-Cost Carbon-Based Perovskite Solar Cells

“…Several materials such as SnO 2 , − ZnO, − CdS, (Ba,Sr)­SnO 3 , and TiO 2 , with different structures, surface treatments, doping methods, and deposition methods have already been used in planar and mesoporous n-i-p perovskite solar cells since 2012. Nevertheless, the bilayer compact/mesoporous TiO 2 layer has been proven as a promising ETL to fabricate high-efficiency stable PSCs.…”