Smartphones are too far to be used for mining as mining requires a lot of power and processing speed which is a smartphone's limit of its feature. It is impossible as even those wired computers needs such effective cooling mechanisms unlike those smartphones that only have thermal pastes and still even overheat.
Its true, i think its not eficient using our smartphone to mining bitcoin. Smartphone not designed for mining bitcoin but for communication. Better keep using proper device to avoid from damage on our smartphone