Ultrasensitive organic-inorganic nanotube thin films of halogenated perovskites as room temperature ammonia sensors

•Comparative study of ammonia sensing carried out for MAPbI3 and MAPbI3−xClx thin films.•The MAPbI3−xClx thin films sensor exhibits a high response which is ~13 times larger than the MAPbI3 sensor.•The MAPbI3−xClx sensor exhibit dense nanostructured tube like structure and large diffusion length of charge carriers.•The MAPbI3−xClx sensor show highly selective and stable ammonia sensing performance than the MAPbI3 sensor.