Issue 9, 2020

Tuning cesium–guanidinium in formamidinium tin triiodide perovskites with an ethylenediammonium additive for efficient and stable lead-free perovskite solar cells

Abstract

Achieving efficient and stable tin-based perovskite solar cells remains challenging. In this work, we incorporate the ethylenediammonium diiodide (EDAI2) additive into a cesium–guanidinium doped formamidinium tin triiodide perovskite with the composition of (CsGA)xFA1−2xSnI3 + y% EDAI2. This new perovskite utilizes the strong hydrogen bonding of the guanidinium cation and the lattice strain relaxation of the small cesium cation as well as the hollowing and passivation effects of the EDAI2 additive. The EDAI2 additive not only yields pinhole-free cubic phase perovskite films but also decreases both shallow and deep trap states in the perovskite films. These effects are pronounced with the increase of substitution of the pair of GA+ and Cs+. The new perovskites are deployed in inverted planar solar cells. A maximum power conversion efficiency (PCE) of 5.01% is achieved with the (CsGA)0.15FA0.70SnI3 + 0% EDAI2 device but the device degrades after storage in a nitrogen-filled glove box for 30 days. Both performance and stability are improved with the addition of EDAI2. A maximum PCE of 5.72% is achieved with the (CsGA)0.15FA0.70SnI3 + 1.0% EDAI2 device. The (CsGA)0.15FA0.70SnI3 + 1.5% EDAI2 devices exhibit a maximum PCE of 5.69% and the performance is further increased to 6.39% after storage in a nitrogen-filled glove box for 4 days; 70% of the initial PCE is retained after 45 days. This study demonstrates the benefit of tuning cation sizes and introducing divalent cations to integrate stabilizing factors into pure Sn perovskites, creating new routes for efficient and stable lead-free perovskite solar cells.

Graphical abstract: Tuning cesium–guanidinium in formamidinium tin triiodide perovskites with an ethylenediammonium additive for efficient and stable lead-free perovskite solar cells

  • This article is part of the themed collection: Perovskites

Supplementary files

Article information

Article type
Paper
Submitted
18 Jul 2020
Accepted
01 Sep 2020
First published
25 Nov 2020
This article is Open Access
Creative Commons BY-NC license

Mater. Adv., 2020,1, 3507-3517

Tuning cesium–guanidinium in formamidinium tin triiodide perovskites with an ethylenediammonium additive for efficient and stable lead-free perovskite solar cells

G. A. Tosado, E. Zheng and Q. Yu, Mater. Adv., 2020, 1, 3507 DOI: 10.1039/D0MA00520G

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