interest in both academic and industrial landscapes for a wide range of applications, including image sensing, [8] optical communication, [9] environmental monitoring, and biomedical applications. [10,11] New emerging applications require selfpowered, cost-effective, highly sensitive, and flexible devices. [12][13][14] These conditions can be fully satisfied using PDs based on perovskite active layers, which combine high ambipolar charge carrier mobility [6,15] with long carrier diffusion length, [16,17] effective light absorption, [18] high defect tolerance [19,20] and low-cost solution processability, [21] making them suitable candidates for high-performance PDs.The route to obtain highly sensitive sensors requires minimizing dark current (J d ) values, which limits the noise (i n ) in devices and maximizes light conversion. To date, few methods exist to reduce the dark current in PDs. They are based on the use of charge-blocking layers to minimize charge injection. [22,23] Other strategies are related to inclusion of additives [24,25] or controlling film crystallization [26,27] to minimize backward charge injection at the electrodes. However, there is a deficit of efforts focused on understanding the role of perovskite composition and its correlation to device J d . Tuning halide composition in perovskites isa powerful approach demonstrated to enhance the performance of perovskite photovoltaic devices where such compositional modifications drive improvements in open-circuit voltage (V oc ) and a reduction in nonradiative voltage losses. Similarly, photodetectors (PDs) operate as light to current conversion devices hence it is relevant to investigate whether performance enhancements can be achieved by similar strategies. Herein, perovskite PDs are fabricated with an inverted photodiode configuration based on a MAPb(I 1-x Br x ) 3 perovskite (MA = methylammonium) active layer over the x = 0-0.25 composition range. Interestingly, it has been found that increasing the Br content up to 0.15 (15%) leads to a significant reduction in dark current (J d ), with values as low as 1.3 × 10 −9 A cm -2 being achieved alongside a specific detectivity of 8.7 × 10 12 Jones. Significantly, it has been observed an exponential relationship between the J d of devices and their V oc over the 0-15% Br range. The superior performances of the 15% Br-containing devices are attributed to the reduction of trap states, a better charge extraction of photogenerated carriers, and an improvement in photoactive layer morphology and crystallinity.