Methylammonium lead bromide is a very perspective hybrid semiconductor material, suitable for high-sensitive, filter-free photodetection of electromagnetic radiation. Herein, we studied the effect of electrode spacing on the output performance and stability of planar-type photodetectors based on high-quality MAPbBr3 single crystals. Such crystals, as large as 4.5×4.5×1.2 mm3 were synthesized via the inverse temperature crystallization method and were further used for the fabrication of planar Au/MAPbBr3/Au photodetectors with variable electrode spacing (in the range between 125 and 25 μm). We report that the electrode spacing has a profound impact on photocurrent densities and key detector parameters (responsivity R, external quantum efficiency EQE, and specific detectivity D*). In the studied fivefold electrode spacing, the photocurrent density increased over 4 times, with decreasing active area of the devices. This effect is attributed to intrinsic photocurrent amplification. Based on the transient photocurrent measurements and calculated key parameters, we determined the device sample with the best output performance. The champion sample with an electrode spacing of 50 μm exhibited great detection ability, especially for a low light intensity of 200 nWcm-2, for which we calculated the R of 19.55 A W-1, EQE of 4253%, and D* of 3.42 × 1012 Jones (cm Hz1/2 W-1). Moreover, the functional stability of this device showed a minimal reduction of photodetection ability after 2000 cycles, which makes it very promising for the next generation of optoelectronic devices.
Keywords: electrode spacing; external quantum efficiency, detectivity; methylammonium lead bromide; perovskites; photodetector; responsivity.