Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Optoelectronic resistive random access memory for neuromorphic vision sensors


Neuromorphic visual systems have considerable potential to emulate basic functions of the human visual system even beyond the visible light region. However, the complex circuitry of artificial visual systems based on conventional image sensors, memory and processing units presents serious challenges in terms of device integration and power consumption. Here we show simple two-terminal optoelectronic resistive random access memory (ORRAM) synaptic devices for an efficient neuromorphic visual system that exhibit non-volatile optical resistive switching and light-tunable synaptic behaviours. The ORRAM arrays enable image sensing and memory functions as well as neuromorphic visual pre-processing with an improved processing efficiency and image recognition rate in the subsequent processing tasks. The proof-of-concept device provides the potential to simplify the circuitry of a neuromorphic visual system and contribute to the development of applications in edge computing and the internet of things.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Non-volatile switching characteristics of ORRAM.
Fig. 2: Light-tunable synaptic characteristics.
Fig. 3: Image memorization and preprocessing.
Fig. 4: Simulations of image recognition in a neuromorphic visual system with ORRAM.

Data availability

The data that support the plots within these paper and other findings of this study are available from the corresponding author upon reasonable request.

Code availability

The simulation codes used for this study are available from the corresponding author upon reasonable request.


  1. Shepherd, R. K., Shivdasani, M. N., Nayagam, D. A., Williams, C. E. & Blamey, P. J. Visual prostheses for the blind. Trends Biotechnol. 31, 562–571 (2013).

    CAS  Article  Google Scholar 

  2. Kolb, H. How the retina works: much of the construction of an image takes place in the retina itself through the use of specialized neural circuits. Am. Sci. 91, 28–35 (2003).

    Article  Google Scholar 

  3. Brady, T. F., Konkle, T., Alvarez, G. A. & Oliva, A. Visual long-term memory has a massive storage capacity for object details. Proc. Natl Acad. Sci. USA 105, 14325–14329 (2008).

    CAS  Article  Google Scholar 

  4. Kim, Y. et al. A bioinspired flexible organic artificial afferent nerve. Science 360, 998–1003 (2018).

    CAS  Article  Google Scholar 

  5. Lee, G. J., Choi, C., Kim, D. H. & Song, Y. M. Bioinspired artificial eyes: optic components, digital cameras, and visual prostheses. Adv. Funct. Mater. 28, 1705202 (2018).

    Article  Google Scholar 

  6. Song, Y. M. et al. Digital cameras with designs inspired by the arthropod eye. Nature 497, 95–99 (2013).

    CAS  Article  Google Scholar 

  7. Jeong, K.-H., Kim, J. & Lee, L. P. Biologically inspired artificial compound eyes. Science 312, 557–561 (2006).

    CAS  Article  Google Scholar 

  8. Ko, H. C. et al. A hemispherical electronic eye camera based on compressible silicon optoelectronics. Nature 454, 748–753 (2008).

    CAS  Article  Google Scholar 

  9. Zhang, L. et al. Self-suspended nanomesh scaffold for ultrafast flexible photodetectors based on organic semiconducting crystals. Adv. Mater. 30, 1801181 (2018).

    Article  Google Scholar 

  10. Choi, C. et al. Human eye-inspired soft optoelectronic device using high-density MoS2–graphene curved image sensor array. Nat. Commun. 8, 1664 (2017).

    Article  Google Scholar 

  11. Lee, W. et al. High-resolution spin-on‐patterning of perovskite thin films for a multiplexed image sensor array. Adv. Mater. 29, 1702902 (2017).

    Article  Google Scholar 

  12. Du, C. et al. Reservoir computing using dynamic memristors for temporal information processing. Nat. Commun. 8, 2204 (2017).

    Article  Google Scholar 

  13. Wu, C., Kim, T. W., Choi, H. Y., Strukov, D. B. & Yang, J. J. Flexible three-dimensional artificial synapse networks with correlated learning and trainable memory capability. Nat. Commun. 8, 752 (2017).

    Article  Google Scholar 

  14. Yao, P. et al. Face classification using electronic synapses. Nat. Commun. 8, 15199 (2017).

    CAS  Article  Google Scholar 

  15. Yu, S. et al. A low energy oxide‐based electronic synaptic device for neuromorphic visual systems with tolerance to device variation. Adv. Mater. 25, 1774–1779 (2013).

    CAS  Article  Google Scholar 

  16. Leydecker, T. et al. Flexible non-volatile optical memory thin-film transistor device with over 256 distinct levels based on an organic bicomponent blend. Nat. Nanotechnol. 11, 769–775 (2016).

    CAS  Article  Google Scholar 

  17. Zhou, F. et al. Low-voltage, optoelectronic CH3NH3PbI3−xClx memory with integrated sensing and logic operations. Adv. Funct. Mater. 28, 1800080 (2018).

    Article  Google Scholar 

  18. Tan, H. et al. An optoelectronic resistive switching memory with integrated demodulating and arithmetic functions. Adv. Mater. 27, 2797–2803 (2015).

    CAS  Article  Google Scholar 

  19. Cheng, Z., Ríos, C., Pernice, W. H., Wright, C. D. & Bhaskaran, H. On-chip photonic synapse. Sci. Adv. 3, e1700160 (2017).

    Article  Google Scholar 

  20. Zhu, D. et al. Resistive random access memory and its applications in storage and nonvolatile logic. J. Semicond. 38, 071002 (2017).

    Article  Google Scholar 

  21. Yang, J. J. et al. Memristive switching mechanism for metal/oxide/metal nanodevices. Nat. Nanotechnol. 3, 429–433 (2008).

    CAS  Article  Google Scholar 

  22. Deb, S. & Chopoorian, J. Optical properties and color-center formation in thin films of molybdenum trioxide. J. Appl. Phys. 37, 4818–4825 (1966).

    CAS  Article  Google Scholar 

  23. Colton, R. J., Guzman, A. M. & Rabalais, J. W. Photochromism and electrochromism in amorphous transition metal oxide films. Acc. Chem. Res. 11, 170–176 (1978).

    CAS  Article  Google Scholar 

  24. Yao, J., Loo, B., Hashimoto, K. & Fujishima, A. Photochromic and electrochromic behavior of electrodeposited MoO3 thin films. J. Electroanal. Chem. 290, 263–267 (1990).

    CAS  Article  Google Scholar 

  25. Wang, S., Fan, W., Liu, Z., Yu, A. & Jiang, X. Advances on tungsten oxide based photochromic materials: strategies to improve their photochromic properties. J. Mater. Chem. C 6, 191–212 (2018).

    CAS  Article  Google Scholar 

  26. Balendhran, S. et al. Two-dimensional molybdenum trioxide and dichalcogenides. Adv. Funct. Mater. 23, 3952–3970 (2013).

    CAS  Article  Google Scholar 

  27. Lei, Y.-H. & Chen, Z.-X. DFT+U study of properties of MoO3 and hydrogen adsorption on MoO3(010). J. Mater. Chem. C. 116, 25757–25764 (2012).

    CAS  Google Scholar 

  28. Yao, J., Yang, Y. & Loo, B. Enhancement of photochromism and electrochromism in MoO3/Au and MoO3/Pt thin films. J. Phys. Chem. B 102, 1856–1860 (1998).

    CAS  Article  Google Scholar 

  29. Zhang, Y., Lee, S.-H., Mascarenhas, A. & Deb, S. An UV photochromic memory effect in proton-based WO3 electrochromic devices. Appl. Phys. Lett. 93, 203508 (2008).

    Article  Google Scholar 

  30. Tsuruoka, T. et al. Effects of moisture on the switching characteristics of oxide-based, gapless-type atomic switches. Adv. Funct. Mater. 22, 70–77 (2012).

    CAS  Article  Google Scholar 

  31. Kumar, A. & Kumar, A. Light-induced metastable defects in a-Se90X10 (X = Sb, In and Ag) thin films. Phase Transit. 88, 939–949 (2015).

    CAS  Article  Google Scholar 

  32. Park, H., Liu, J. & Wagner, S. Saturation of the light‐induced defect density in hydrogenated amorphous silicon. Appl. Phys. Lett. 55, 2658–2660 (1989).

    CAS  Article  Google Scholar 

  33. Street, R. & Davies, D. Kinetics of light induced defect creation in organic solar cells. Appl. Phys. Lett. 102, 043305 (2013).

    Article  Google Scholar 

  34. Lei, S. et al. Optoelectronic memory using two-dimensional materials. Nano Lett. 15, 259–265 (2014).

    Article  Google Scholar 

Download references


This work was supported by the Research Grants Council of Hong Kong (PolyU 152053/18E), the Hong Kong Polytechnic University (G-YBPS, 1-ZVGH, 1-ZE25 and G-SB79) and the National Natural Science Foundation of China (61851402 and 61421005). F.Z. thanks Y. Liu, Y. Zhang and M. Wang for helpful discussions, S. H. Cheung and S. K. So for the photothermal deflection spectroscopy test and J. Zhang for the ultraviolet photoelectron spectroscopy test.

Author information

Authors and Affiliations



Y.C. and F.Z. conceived and designed the project. Y.C. supervised the project. F.Z., T.H.C., J.W. and Z.L. performed the experiments, including both fabrication and characterization. Z.Z., F.Z., J.C., S.Y. and J.K. performed the simulations. J.C. performed the density functional theory calculations. F.Z., N.Z., Y.C., S.Y., J.K. and H.-S.P.W. analysed the data. F.Z. and Y.C. co-wrote the paper. All the authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Yang Chai.

Additional information

Peer review information: Nature Nanotechnology thanks Dae-Hyeong Kim and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Zhou, F., Zhou, Z., Chen, J. et al. Optoelectronic resistive random access memory for neuromorphic vision sensors. Nat. Nanotechnol. 14, 776–782 (2019).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Further reading


Quick links

Find nanotechnology articles, nanomaterial data and patents all in one place. Visit Nano by Nature Research