To Be Higher and Stronger—Metal Oxide Electron Transport Materials for Perovskite Solar Cells

Abstract

Organometallic mixed halide perovskite solar cells (PSCs) have emerged as a promising photovoltaic technology with increasingly improved device efficiency exceeding 24%. Charge transport layers, especially electron transport layers (ETLs), are verified to play a vital role in device performance and stability. Recently, metal oxides (MOs) have been widely studied as ETLs for high‐performance PSCs due to their excellent electronic properties, superb versatility, and great stability. This Review briefly discusses the development of PSCs' architecture and outlines the requirements for MO ETLs. Additionally, recent progress of MO ETLs from preparation to optimization for efficient PSCs is systematically summarized and highlighted to associate the versatility of MO ETLs with the performance of devices. Finally, a summary and prospectives for the future development of MO ETLs toward practical application of high‐performance PSCs are drawn.

Incorporating a Polar Molecule to Passivate Defects for Perovskite Solar Cells

“…Thus, it is difficult to achieve high performance of PSCs with bare ZnO ETLs. Recently, doping and surface passivation techniques have been widely applied to improve the intrinsic defects of ZnO …”

Advances in design engineering and merits of electron transporting layers in perovskite solar cells

“…103,104 The optoelectronic properties of n-type semiconducting ZnO, such as a suitable conduction band energy level (BÀ4.17 eV for the CBM), large optical bandgap of 3.3 eV, high electronic mobility and high transmittance, are promising for applications in PSCs. [105][106][107] In addition, the low-temperature processed ZnO nanocrystalline thin films are favourable for flexible devices. 64 Nevertheless, ZnO could cause decomposition of organometal halide perovskites, which may impede its largescale application in PSCs.…”

Recent Advances in Carbon Nanotube Utilizations in Perovskite Solar Cells

“…The ETL in PSCs plays a critical role in selectively extracting electrons and blocking holes, and transporting photogenerated electrons to the corresponding electrode. [ 107,108 ] Thus, ETLs employed in high‐performance PSCs should simultaneously satisfy several requirements: favorable energy‐level alignment for easy electron extraction, high electron mobility to ensure fast electron transportation, high optical transmittance allows as much sunlight to enter the perovskite layer, and outstanding stability for long‐term device operation. [ 108 ] Several kinds of ETLs, such as metal oxides, metal sulfides, and organic materials, have been reported.…”

“…[ 107,108 ] Thus, ETLs employed in high‐performance PSCs should simultaneously satisfy several requirements: favorable energy‐level alignment for easy electron extraction, high electron mobility to ensure fast electron transportation, high optical transmittance allows as much sunlight to enter the perovskite layer, and outstanding stability for long‐term device operation. [ 108 ] Several kinds of ETLs, such as metal oxides, metal sulfides, and organic materials, have been reported. [ 109,110 ] TiO 2 and SnO 2 are the most popular ETLs currently in state‐of‐the‐art n–i–p structured PSCs.…”