Fig. 2: Optical and photoconductivity measurements.

a Normalized UV-Vis absorbance spectra of horizontal (in yellow) and vertical (in red) LDP thin films. b Electronic band structure of TMA₂MAPb₂I₇ from DFT simulations with the inset showing the electron and hole effective masses along the three conventional unit cell axes. Photo-induced sheet THz conductivity dynamics of the c horizontal (in yellow) and d vertical (in red) LDP thin films. The excitation fluence (excitation intensity per laser pulse) was varied from 5.3 μJ cm⁻² up to 53.8 μJ cm⁻² in a similar manner for both types of LDP thin films. e Effective electron-hole sum mobility estimates extracted from the conductivity values immediately post photoexcitation. Such analysis corroborates the vertical alignment of the inorganic chain as detected by X-rays, resulting in a corresponding boost in the charge-carrier mobility.