For full experimental details please refer to main publication. All figures describe methylammonium lead iodide samples. ‘Figure 1’ includes: photoluminescence quantum efficiency at different laser intensities and associated fit (tab 1), ln of time resolved photoluminescence counts as a function of time (tab 2), the initial time resolved photoluminescence counts as a function of initial excitation density (tab 3) and extracted first order decay rates for sample 1 and 2 (tab 4). ‘Figure 2’ includes: inverse excitation density as a function of time, as measured in transient absorption spectroscopy, associated fit, and raw DT/T data (tab 1), and extracted second order decay rates from both photoluminescence quantum efficiency/time resolved photoluminescence and transient absorption spectroscopy for four samples (tab 2). ‘Figure 3’ includes: spread of decay rate and ratio of radiative rate ratios extracted from microscopic photoluminescence quantum efficiency measurements at the microscale (tab 1), measured and predicted photoluminescence quantum efficiency for sample 1 and 2 (tab 2) and ratio of total to radiative second order rate for all four samples (tab 3). ‘Figure 4’ includes: predicted current voltage curves for a measured sample, with a range of decay rate conditions (tab 1) and efficiency as a function of first order rate and ratio of radiative to total second order rate (tab 2).