Stable all-inorganic CsPbX₃ perovskite nanocrystals (PNCs, where X is Cl, Br or I) have optical properties tuneable across the UV-Vis wavelength range and have high photoluminescence quantum yield (Figure 1a). To enhance their optical and environmental stability, we adopted a number of approaches, from optimizing the ligand binding to overgrowing the nanocrystals with perovskite shell [1]. The quality of the NC surface affects their potential for applications in electronics and optoelectronics [2-6], hence we explore the slow dynamics of charge transfer processes in graphene/PNC heterostructures (Fig. 1b) [2] and demonstrate that optically induced Stark effect governs the optical performance of the NCs [3]. We find that in these PNCs, the surface Pb-defects can provide surface trap states, resulting in charge accumulation, which in turns affects the properties of perovskite layers and their heterostructure devices. Out theoretical and experimental studies evaluated charge dynamics associated with all-inorganic PNCs, revealing novel effects, such as huge hysteresis of the FET transfer characteristics [2] and magnetic-field-depended charge transfer [4]. Based on these results we demonstrate a perovskite based graphene photon sensors with exceptionally high photoresponsivity, R, up to 10⁶ A/W and spectral selectivity tunable by the PNC composition [1-3] (Figure 1c). The stability of all-inorganic PNCs allowed us to formulation the inks for inkjet printing of photodetectors (Fig. c) [5-6], which have comparable performance to those produced by drop coating, confirming that our PeNCs can withstand the conditions (high T, illumination, etc) of this additive manufacturing process, opening up exciting opportunities for advanced fabrication of printed flexible and wearable optoelectronics. 

 

[1] C. Zhang, et al., Nanoscale 11, 13450 (2019); Z. Ma et.al., ACS Applied Nano Materials 4 (8), 8383 (2021); C. Zhang et.al., Advanced Functional Materials 31 (19), 2100438 (2021)

[2] N.D. Cottam et al., ACS Appl. Electron. Mater. 2, 147 (2020)

[3]  N.D. Cottam et al., Adv. Optical Mater. 9, 2100104 (2021)

[4] N. D. Cottam, et al. Adv. Electron. Mater. 9, 2, 2200995 (2023).

[5] J. S. Austin, et al. Nanoscale 15, 5, 2134 (2023). 

[6] F. Wang, et al. Adv. Funct. Mater. 31, 5, 2007478(2021).