Room-Temperature Processed Nb₂O₅ as the Electron-Transporting Layer for Efficient Planar Perovskite Solar Cells

Abstract

In this work, we demonstrate high-efficiency planar perovskite solar cells (PSCs), using room-temperature sputtered niobium oxide (NbO) as the electron-transporting layer (ETL). Widely spread ETL-like TiO often requires high-temperature (>450 °C) sintering, which is not desired for the fabrication of flexible devices. The amorphous NbO (labeled as a-NbO) ETL, without any heat treatment, can give a best power conversion efficiency (PCE) of 17.1% for planar PSCs. Interestingly, the crystalline NbO (labeled as c-NbO), with high-temperature (500 °C) annealing, results in a very similar PCE of 17.2%, indicating the great advantage of a-NbO in energy saving. We thus carried out a systematical investigation on the properties of the a-NbO film. The Hall effect measurements indicate both high mobility and conductivity of the a-NbO film. Kelvin probe force microscopy measurements define the Fermi levels of a-NbO and c-NbO as -4.31 and -4.02 eV, respectively, which allow efficient electron extraction at the NbO/perovskite interface, regardless of the additional heat treatment on NbO film. Benefitting from the low-temperature process, we further demonstrated flexible PSCs based on a-NbO, with a considerable PCE of 12.1%. The room-temperature processing and relatively high device performance of a-NbO suggest a great potential for its application in optoelectrical devices.

Chlorine‐modified SnO2 electron transport layer for high‐efficiency perovskite solar cells

“…Consequently, it is imperative to develop a low-temperature fabrication process for simple-structured planar PSCs. To improve the PCE of low-temperature planar PSCs, various ETLs have been developed in the past several years, including TiO 2 , [8][9][10][11][12] SnO 2 , [13][14][15][16][17][18] ZnO, [19][20][21] Nb 2 O 5 , [22][23][24] WO x , 25 and Zn 2 SnO 4 nanoparticle thin film. 26,27 Among them, SnO 2 is a promising candidate for planar PSCs.…”

14.1% CsPbI3 Perovskite Quantum Dot Solar Cells via Cesium Cation Passivation

“…Due to the great efforts on CQDs synthesis modification, [7][8][9] surface passivation, [10][11][12] and device fabrication optimization, [13][14][15][16] PbS QD solar cells continue to progress at an extraordinary rate, improving overall efficiencies by ≈1% per year and currently have a certified power conversion efficiency (PCE) exceeding 12%. [18][19][20][21][22][23][24][25][26][27][28] However, the challenging stability issues of these hybrid perovskites further motivate the research of all-inorganic perovskites (CsPbX 3 , X = Cl − , Br − , I − or mixed halides) without any volatile organic components. [18][19][20][21][22][23][24][25][26][27][28] However, the challenging stability issues of these hybrid perovskites further motivate the research of all-inorganic perovskites (CsPbX 3 , X = Cl − , Br − , I − or mixed halides) without any volatile organic components.…”

Realizing Stable Artificial Photon Energy Harvesting Based on Perovskite Solar Cells for Diverse Applications

“…The element compositions of the ETL were characterized by X‐ray photoelectron spectroscopy (XPS) and are shown in Figure S10 (Supporting Information). The binding energy in the range from 204 eV to 213 eV is related to the Nb 3d transition,38,39 and the Nb/(Nb+Ti) ratio has a positive correlation with the element ratio in the precursor mixture, which suggests the successful Nb doping. The energy band of the ETL with various Nb doping ratios was determined by the UV–vis absorption spectra together with the ultraviolet photoelectron spectroscopy (UPS) in Figure S11 (Supporting Information).…”