Table 2. Comparison of the band extrema predicted in Table 1 to those predicted by DFT calculations for a wide range of cubic double perovskites. The B and B′ orbitals that contribute to a band were determined from DFT density-of-states calculations but, in principle, could come from chemical reasoning or experimental information. For a given perovskite, the k points corresponding to band extrema that are calculated to be within 0.1 eV of each other are listed together.

Compound	Valence band maximum				Conduction band minimum				Bandgap	Reference
	B	B′	Pred.	Calc.	B	B′	Pred.	Calc.
Cs2AgBiBr6 a	Ag 4dz2	Bi 6s	X	X	Ag 5s	Bi 6p	L	L	Indirect	12
Cs2AgInCl6	Ag 4dz2 b	Null	Γ	Γ	Ag 5s	In 5s	Γ	Γ	Direct	18
Cs2AgSbBr6 a	Ag 4dz2	Sb 5s	X	X	Ag 5s	Sb 5p	L	L	Indirect	46
Cs2AgTlBr6 a	Ag 4dz2 b	Null	Γ	Γ	Ag 5s	Tl 6s	Γ	Γ	Direct	17
Cs2AgYCl6	Ag 4dz2 b	Null	Γ & X	L	Ag 5s	Null c	Γ	Γ	Indirect	47
Cs2KBiCl6	K 3p	Bi 6s	L	L	K 4p d	Bi 6p	Γ	Γ & L	Direct	See ESI
Cs2KYCl6	Null	Null	Γ & X	Γ & X	Null	Y 4dxy e	Γ	Γ	Direct	44
Cs2NaBiCl6	Null	Bi 6s	X	X	Na 3p d	Bi 6p	Γ	Γ & L	Indirect	See ESI
Cs2NaInBr6 a , f	Null	Null	Γ & X	Γ & X	Null	In 5s	Γ	Γ	Direct	48 and 49
(MA)2TlBiBr6 g	Tl 6s	Bi 6s	Γ	Γ	Tl 6p	Bi 6p	Γ	Γ	Direct	19
Cs2TlTlCl6 h	Tl 6s	Null	X	X	Tl 6p	Tl 6s	L	L	Indirect	50
Cs2HfIV□Cl6 a	Null	Null	Γ & X	Γ & X	Hf 5dxy e	Null	Γ & X	Γ & X	Indirect	41
Cs2PdIV□Br6	Null	Null	Γ & X	Γ & X	Pd 4dz2	Null	X	X	Direct	40
Cs2SnIV□I6 a	Null	Null	Γ & X	Γ	Sn 5s	Null	Γ	Γ	Direct	38
Cs2TeIV□I6	Te 6s	Null	X	X	Te 6p	Null	L	L	Indirect	39
Cs2TiIV□I6 a	Null	Null	Γ & X	Γ	Ti 3dxy e	Null	Γ & X	Γ & X	Indirect	42

^aIsostructural compounds with other halides are known. These compounds are also well-described by the LCAO model.

^bThe d_z² orbital is degenerate with the d_x²–y² orbital.

^cBands originating from the Y 4d_xy orbitals π-bonding with the halides are also present near the CBM but are at slightly higher energies and don't interact with the σ-bonding Ag 5s states (see ESI).

^dSee ESI for extended discussion of the appearance of alkali p character in the conduction band of these materials.

^eThe d_xy orbital is degenerate with d_xz and d_yz orbitals.

^fThe calculated density of states is only available for the bromide, which has not been synthesized experimentally. The isostructural Cs₂NaInCl₆ has been synthesized.

^g“MA” corresponds to CH₃NH₃⁺.

^hThe reported density of states does not distinguish between Tl⁺ and Tl³⁺ contributions. These were determined based on chemical reasoning.