Open AccessStrain Tuning via Larger Cation and Anion Codoping for Efficient and Stable Antimony‐Based Solar Cells
Author(s) -
Nie Riming,
Lee Kyoung Su,
Hu Manman,
Seok Sang Il
Publication year - 2021
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.202002391
Subject(s) - antimony , materials science , energy conversion efficiency , doping , band gap , ion , solar cell , optoelectronics , photovoltaic system , strain (injury) , chemistry , electrical engineering , medicine , organic chemistry , metallurgy , engineering
Strain induced by lattice distortion is one of the key factors that affect the photovoltaic performance via increasing defect densities. The unsatisfied power conversion efficiencies (PCEs) of solar cells based on antimony chalcogenides (Sb‐Chs) are owing to their photoexcited carriers being self‐trapped by the distortion of Sb 2 S 3 lattice. However, strain behavior in Sb‐Chs‐based solar cells has not been investigated. Here, strain tuning in Sb‐Chs is demonstrated by simultaneously replacing Sb and S with larger Bi and I ions, respectively. Bi/I codoped Sb 2 S 3 cells are fabricated using poly[2,6‐(4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b']dithiophene)‐alt‐4,7‐(2,1,3‐enzothiadiazole)] as the hole‐transporting layer. Codoping reduced the bandgap and rendered a bigger tension strain (1.76 × 10 −4 ) to a relatively smaller compression strain (−1.29 × 10 −4 ). The 2.5 mol% BiI3 doped Sb 2 S 3 cell presented lower trap state energy level than the Sb 2 S 3 cell; moreover, this doping amount effectively passivated the trap states. This codoping shows a similar trend even in the low bandgap Sb 2 (S x Se 1‐x ) 3 cell, resulting in 7.05% PCE under the standard illumination conditions (100 mW cm −2 ), which is one of the top efficiencies in solution processing Sb 2 (S x Se 1‐x ) 3 solar cells. Furthermore, the doped cells present higher humidity, thermal and photo stability. This study provides a new strategy for stable Pb‐free solar cells.