TY - JOUR
T1 - Limitations of Cs 3 Bi 2 I 9 as Lead-Free Photovoltaic Absorber Materials
AU - Ghosh, Biplab
AU - Wu, Bo
AU - Mulmudi, Hemant Kumar
AU - Guet, Claude
AU - Weber, Klaus
AU - Sum, Tze Chien
AU - Mhaisalkar, Subodh
AU - Mathews, Nripan
N1 - Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/10/17
Y1 - 2018/10/17
N2 - Lead (Pb) halide perovskites have attracted tremendous attention in recent years because of their rich optoelectronic properties, which have resulted in more than 22% power conversion efficient photovoltaics (PVs). Nevertheless, Pb-metal toxicity remains a huge hurdle for extensive applications of these compounds. Thus, alternative compounds with similar optoelectronic properties need to be developed. Bismuth possesses electronic structure similar to that of lead with the presence of ns 2 electrons that exhibit rich structural variety as well as interesting optical and electronic properties. Herein, we critically assess Cs 3 Bi 2 I 9 as a candidate for thin-film solar cell absorber. Despite a reasonable optical band gap (∼2 eV) and absorption coefficient, the power conversion efficiency of the Cs 3 Bi 2 I 9 mesoscopic solar cells was found to be severely lacking, limited by the poor photocurrent density. The efficiency of the Cs 3 Bi 2 I 9 solar cell can be slightly improved by changing the stoichiometry of the precursor solutions, which is most probably due to the reduction in nonradiative defects as evident from our single-crystal photoluminescence spectroscopy. However, detailed investigations on pristine Cs 3 Bi 2 I 9 reveal that zero-dimensional molecular crystal structure remains one of the main bottlenecks in achieving high performance. On the basis of our comprehensive studies, we have proposed that a continuous network of three-dimensional crystal structure should be another major criterion in addition to proper band gap and suitable optical properties of the future PV compounds.
AB - Lead (Pb) halide perovskites have attracted tremendous attention in recent years because of their rich optoelectronic properties, which have resulted in more than 22% power conversion efficient photovoltaics (PVs). Nevertheless, Pb-metal toxicity remains a huge hurdle for extensive applications of these compounds. Thus, alternative compounds with similar optoelectronic properties need to be developed. Bismuth possesses electronic structure similar to that of lead with the presence of ns 2 electrons that exhibit rich structural variety as well as interesting optical and electronic properties. Herein, we critically assess Cs 3 Bi 2 I 9 as a candidate for thin-film solar cell absorber. Despite a reasonable optical band gap (∼2 eV) and absorption coefficient, the power conversion efficiency of the Cs 3 Bi 2 I 9 mesoscopic solar cells was found to be severely lacking, limited by the poor photocurrent density. The efficiency of the Cs 3 Bi 2 I 9 solar cell can be slightly improved by changing the stoichiometry of the precursor solutions, which is most probably due to the reduction in nonradiative defects as evident from our single-crystal photoluminescence spectroscopy. However, detailed investigations on pristine Cs 3 Bi 2 I 9 reveal that zero-dimensional molecular crystal structure remains one of the main bottlenecks in achieving high performance. On the basis of our comprehensive studies, we have proposed that a continuous network of three-dimensional crystal structure should be another major criterion in addition to proper band gap and suitable optical properties of the future PV compounds.
KW - Cs Bi I
KW - bismuth-based perovskite
KW - cathodoluminescence
KW - lead-free
KW - perovskite solar cell
KW - photovoltaics
UR - http://www.scopus.com/inward/record.url?scp=85054133109&partnerID=8YFLogxK
U2 - 10.1021/acsami.7b14735
DO - 10.1021/acsami.7b14735
M3 - Article
SN - 1944-8244
VL - 10
SP - 35000
EP - 35007
JO - ACS applied materials & interfaces
JF - ACS applied materials & interfaces
IS - 41
ER -