AIn 4 S 6 Cl (A = Rb and Cs) and Pb 5 Sn 3 Q 10 Cl 2 (Q = S and Se): quaternary chalcohalides with mixed anionic coordination exhibit photocurrent responses.

Mixed-anionic compounds have caught considerable attention due to their flexible coordination manners and abundant physical properties. Four new chalcohalides RbIn 4 S 6 Cl (1), CsIn 4 S 6 Cl (2), Pb 5 Sn 3 S 10 Cl 2 (3) and Pb 5 Sn 3 Se 10 Cl 2 (4) were successfully obtained by the high-temperature halide salt flux method. Compounds 1 and 2 have layered structures that consist of octahedral InS 6 and aliovalent-anionic InS 3 Cl units. Compounds 3 and 4 feature 3-D structural frameworks built by [Pb 4 SnQ 8 Cl 4 ] 6- and [PbSn 2 Q 6 ] 2- (Q = S and Se) polyhedral chains, in which partial Pb 2+ cations are coordinated by Q 2- and Cl - anions. Compounds 1-4 have optical band gaps close to the wavelength range of visible light and exhibit significant photocurrent responses of 28.75 nA cm -2 , 55.12 nA cm -2 , 19.58 mA cm -2 , and 36.12 μA cm -2 with on/off ratios 30.0, 2.5, 15.7 and 2.6, respectively, implying their potential for photovoltaic applications. To the best of our knowledge, compound 3 has the largest photocurrent response among all non-oxides. In addition, the activation energies of 1-4 are well below 0.3 eV, which makes these compounds interesting for potential applications in electrochemical devices. This work sheds light on the exploration of promising photocurrent response materials in the mixed-anionic compound system.