Micro-engineered CH$_3$NH$_3$PbI$_3$ nanowire/graphene phototransistor   for low intensity light detection at room temperature
  Methylammonium lead iodide perovskite has revolutionized the field of third generation solid-state solar cells leading to simple solar cell structures1 and certified efficiencies up to 20.1%. Recently the peculiar light harvesting properties of organometal halide perovskites have been exploited in photodetectors where responsivities of ~3.5 A/W and 180 A/W have been respectively achieved for pure perovskite-based devices and hybrid nanostructures. Here, we report on the first hybrid phototransistors where the performance of a network of photoactive Methylammonium Lead Iodide nanowires (hereafter MAPbI$_3$NW) are enhanced by CVD-grown monolayer graphene. These devices show responsivities as high as ~2.6x10$^6$ A/W in the visible range showing potential as room-temperature single-electron detector. 
M. Spina, M. Lehmann, B. N\'afr\'adi, L. Bernard, E. Bonvin, R.   Ga\'al, A. Magrez, L. Forr\'o, E. Horv\'ath
cond-mat.mes-hall