The optical properties of (NH 3 (CH 2 ) 7 NH 3 ) 2 Sn 3 I 10 reflect the unusual defect-ordered nature of the crystal structure. This is most notable in the observed photoluminescence spectrum: the emission spectrum is very broad (FHWM > 127 nm), which is usually indicative of strong electron-phonon coupling of some variety. The center of the photoluminescence emission spectrum nearly overlaps with the absorption onset, but the emission spectrum is Stokes shifted by up to 1.3 eV from the excitation spectrum. While self-trapped excitons also exhibit very large Stoke shifts (>1 eV) and very broad spectra (FWHM > 100 nm), the excitation spectra and absorption spectra tend to overlap; thus, the emission spectrum tends to be red-shifted from the absorption onset, unlike what is observed here.