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Intrinsic Defect Limit to the Electrical Conductivity and a Two‐Step p‐Type Doping Strategy for Overcoming the Efficiency Bottleneck of Sb 2 S 3 ‐Based Solar Cells
Author(s) -
Cai Zenghua,
Dai Chen-Min,
Chen Shiyou
Publication year - 2020
Publication title -
solar rrl
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.544
H-Index - 37
ISSN - 2367-198X
DOI - 10.1002/solr.201900503
Subject(s) - doping , dopant , electrical resistivity and conductivity , passivation , materials science , bottleneck , energy conversion efficiency , optoelectronics , carrier lifetime , conductivity , photovoltaic system , analytical chemistry (journal) , condensed matter physics , nanotechnology , chemistry , electrical engineering , physics , computer science , silicon , layer (electronics) , embedded system , engineering , chromatography
The photovoltaic efficiency increase in Sb 2 S 3 ‐based solar cells has stagnated for 5 years since the highest efficiency of 7.5% was achieved in 2014. One important bottleneck is the high electrical resistivity of Sb 2 S 3 . The first‐principle calculations reveal that the high‐resistivity results from the compensation between the intrinsic donor V S and acceptors V Sb , Sb S , and S Sb which have comparably high concentration (low formation energy). The compensation also limits the improvement of conductivity through direct extrinsic doping. Further calculations of O dopants show that O S has low formation energy, so the dominant intrinsic donor V S can be passivated by O and thus the p‐type doping limit imposed by V S can be overcome. Meanwhile, other p‐type limiting and recombination‐center donor defects can be suppressed under the S‐rich condition, which explains why the highest efficiency is achieved in O‐doped Sb 2 S 3 after sulfurization. Given the unexpected beneficial effects of O doping and sulfurization, a two‐step doping strategy is proposed for overcoming the efficiency bottleneck: 1) use O to passivate the V S and S‐rich condition to suppress other detrimental defects, making p‐type doping feasible and minority carrier lifetime long; 2) introduce other p‐type dopants to increase hole carrier concentration.