Tailoring in-gap states for optimizing the band gap in mixed-valent bromometallates, towards lead-free photovoltaics

Tailoring in-gap states for optimizing the band gap in mixed-valent bromometallates, towards lead-free photovoltaics Full article

Journal

Dalton Transactions
ISSN: 1477-9234 , E-ISSN: 1477-9226

Output data

Year: 2026, Volume: 55, Number: 12, Pages: 5013-5026 Pages count : 14 DOI: 10.1039/d5dt02874d

Authors

Shestimerova Tatiana A. ¹ , Klykova Angelina P. ¹ , Medved'ko Alexey V. ² , Khrustalev Victor N. ^3,2 , Bykov Mikhail A. ¹ , Pankratov Denis A. ¹ , Presniakov Igor A. ^4,1 , Kuznetsov Alexey N. ^1,5 , Vatsadze Sergey Z. ^1,2 , Shevelkov Andrei V. ¹

Affiliations

1	Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia
2	Zelinsky Institute of Organic Chemistry of RAS, Moscow, Russia
3	Peoples’ Friendship University of Russia (RUDN University), Moscow, Russia
4	5MSU-BIT University, Shenzhen, Guangdong Province, P. R. China
5	Kurnakov Institute of Inorganic Chemistry, Moscow, Russia

Motivated by the task to replace toxic lead halide perovskites with lead-free environmentally benign light-harvesting materials for photovoltaics, we have synthesized two new hybrid bromometallates, (AH2)4[Sb2Br10(SbBr6)2(Br)2] (1) and (AH2)2[(BiBr6)(SbBr6)]·2H2O (2), where A = 1,5-dimethyl-3,7-diazabicyclo[3.3.1]nonane. Their crystal structures show combinations of Sb3+/Sb5+ (1) or Bi3+/Sb5+ (2) centers each surrounded by six Br− anions forming distorted (Sb3+ or Bi3+) or almost regular (Sb5+) octahedra. These octahedra are arranged in the crystal structure in a perfectly ordered way owing to weak Br⋯Br interactions within the inorganic anionic part and to hydrogen bonds linking inorganic anions and organic cations. The electronic structures of both compounds are alike in that they have M3+/Br− states (M = Sb or Bi) dominating the top of the valence band and acceptor in-gap states formed by the Sb5+/Br− interactions. Such an electronic structure leads to the reduced band gap of 1.27 (1) and 1.58 eV (2), favorable for creating light-harvesting materials for photovoltaics. We support our data by powder and single-crystal X-ray diffraction study, 121Sb Mossbauer spectroscopy, and optical spectroscopy. We infer that tailoring the band gap is a very important step on the way to lead-free light-harvesting materials for photovoltaic applications.

Shestimerova T.A. , Klykova A.P. , Medved'ko A.V. , Khrustalev V.N. , Bykov M.A. , Pankratov D.A. , Presniakov I.A. , Kuznetsov A.N. , Vatsadze S.Z. , Shevelkov A.V.
Tailoring in-gap states for optimizing the band gap in mixed-valent bromometallates, towards lead-free photovoltaics
Dalton Transactions. 2026. V.55. N12. P.5013-5026. DOI: 10.1039/d5dt02874d WOS Scopus OpenAlex

Submitted:	Dec 2, 2025
Published online:	Feb 27, 2026

≡ Web of science:	WOS:001710842900001
≡ Scopus:	2-s2.0-105032480601
≡ OpenAlex:	W7131779680