High-bandwidth light inputting multilevel photoelectric memory based on thin-film transistor with a floating gate of CsPbBr₃/CsPbI₃ blend quantum dots

The electronic-photonic convergent systems can overcome the data transmission bottleneck for microchips by enabling processor and memory chips with high-bandwidth optical input/output. However, current silicon-based electronic-photonic systems require various functional devices/components to convert high-bandwidth optical signals into electrical ones, thus making further integrations of sophisticated systems rather difficult. Here, we demonstrate thin-film transistor-based photoelectric memories employing CsPbBr₃/CsPbI₃ blend perovskite quantum dots (PQDs) as a floating gate, and multilevel memory cells are achieved under programming and erasing modes, respectively, by imputing high-bandwidth optical signals. For different bandwidth light input (i.e. 500–550, 575–650 and 675–750 nm) with the same intensity, three levels of programming window (i.e. 3.7, 1.9 and 0.8 V) and erasing window (i.e. −1.9, −0.6 and −0.1 V) are obtained under electrical pulses, respectively. This is because the blend PQDs have two different bandgaps, and different amounts of photo-generated carriers can be produced for different wavelength optical inputs. It is noticed that the 675–750 nm light inputs have no effects on both programming and erasing windows because of no photo-carriers generation. Four memory states are demonstrated, showing enough large gaps (1.12–5.61 V) between each other, good data retention and programming/erasing endurance. By inputting different optical signals, different memory states can be switched easily. Therefore, this work directly demonstrates high-bandwidth light inputting multilevel memory cells for novel electronic-photonic systems. (paper)