Highly Efficient Amorphous Zn₂SnO₄ Electron-Selective Layers Yielding over 20% Efficiency in FAMAPbI₃-Based Planar Solar Cells

Abstract

Amorphous Zn 2 SnO 4 (am-ZTO) films with extreme surface uniformity, high electron mobility, and fewer charge traps were successfully developed by controlling the concentrations of 2methoxyethanol solutions containing the 2:1 stoichiometric ratio of Zn to Sn. For the first time, we demonstrate that solution-processed am-ZTO thin films are highly efficient as an electron-selective layer (ESL) for mixed perovskite solar cells (PSCs). When am-ZTO ESLs were combined with bandgap-tuned FAMAPbI 3 perovskites, a champion efficiency of 20.02% was achieved. In addition, devices based on am-ZTO showed a statistical reproducibility of 18.38 ± 0.61% compared to 15.85 ± 1.02% of the TiO 2 -based counterparts. This high efficiency is achieved by the significant increase in both the short-circuit current and opencircuit voltage owing to improved charge transport/extraction and recombination. Moreover, am-ZTO ESL-based devices show improved stability and reduced hysteresis, which is a promising result for future PSC research.

Metal Oxide Charge Transport Layers for Efficient and Stable Perovskite Solar Cells

“…The designed ZSO ETL exhibited effective electron collection in the ETL and related interfaces, yielding a PCE of 16.5% on flexible substrate. More recently, amorphous ZSO ETL has been reported using a facile sol–gel derived spin‐coating for planar PSCs . Without any reactants, dopants, or atmosphere controls, amorphous ZSO films with an extremely uniform surface and high electron mobility were easily prepared from acetate sources, which resulted in rapid charge extraction with little recombination in PSCs, resulting in a PCE of 20.02% with enhanced stability and reduced hysteresis.…”

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

“…109,110 For example, Feng et al deposited amorphous Nb 2 O 5 ETL for large-area rigid PSCs and flexible planar PSCs using an e-beam evaporation method, obtaining PCEs of 18.59% and 15.56%, respectively. 111 Moreover, other binary metal oxides, such as WOx 112,113 and In 2 O 3 , 114,115 and ternary metal oxides, such as Zn 2 SnO 4 , 116,117 BaSnO 3 118,119 and SrTiO 3 , 120,121 have been proposed for highefficiency PSCs as listed in Table 1. Based on eqn (2), the free electron concentration is dependent on the charge trapping-de-trapping process via defects in the metal oxide nanocrystals.…”

Device Physics of the Carrier Transporting Layer in Planar Perovskite Solar Cells

“…The fullerene based materials and their derivatives are also intensively studied as electron transport materials, such as the phenyl‐C 61 ‐butyric acid methyl ester (PCBM), C 60 bathocuprione (BCP), etc. Meanwhile, the relatively low‐cost nonfullerenes, e.g., 3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′] dithiophene) (ITIC) and their derivatives that possess excellent optical and electrical properties compared with their fullerene counterparts are also promising for highly efficient and stable PVSCs . Regarding the inorganic semiconductor materials, metal oxides possess superior stability and tunable optical and electrical properties compared with the organic semiconductor materials.…”