Bio

Dr. Koosha Nassiri Nazif received his Ph.D. in Electrical Engineering (Jan 2022) and his M.S. in Mechanical Engineering (2016) from Stanford University. Along the way, he worked at Apple (2019) on OLED/LCD displays and at HP Labs (2017) on 3D electronics thermal management. He is currently a post-doctoral scholar at Stanford developing novel flexible optoelectronic devices, including solar cells and wearable sensors, based on 2D transition metal dichalcogenides.

Honors & Awards

  • VPGE Graduate Scholar Award, Stanford University (2018)
  • Teaching Fellowship Award, Electrical Engineering Department, Stanford University (2018)
  • Stanford Graduate Engineering Fellowship Award, Stanford University (2014)
  • Professor Joel H. Ferziger Memorial Fellowship Award, Stanford University (2014)

Professional Education

  • Doctor of Philosophy, Stanford University, EE-PHD (2022)
  • Master of Science, Stanford University, ME-MS (2016)
  • B.Sc., Sharif University of Technology, Mechanical Engineering (2014)

Stanford Advisors

  • Eric Pop, Postdoctoral Faculty Sponsor

Contact

  • Academic
    koosha@stanford.edu
    University - Scholar Department: Electrical Engineering Position: Postdoctoral Scholar

Additional Info

  • Mail Code: 3030

Links

Lab Affiliations

All Publications

  • High-Efficiency WSe2 Photovoltaic Devices with Electron-Selective Contacts. ACS nano Kim, K., Andreev, M., Choi, S., Shim, J., Ahn, H., Lynch, J., Lee, T., Lee, J., Nazif, K. N., Kumar, A., Kumar, P., Choo, H., Jariwala, D., Saraswat, K. C., Park, J. 2022

    Abstract

    A rapid surge in global energy consumption has led to a greater demand for renewable energy to overcome energy resource limitations and environmental problems. Recently, a number of van der Waals materials have been highlighted as efficient absorbers for very thin and highly efficient photovoltaic (PV) devices. Despite the predicted potential, achieving power conversion efficiencies (PCEs) above 5% in PV devices based on van der Waals materials has been challenging. Here, we demonstrate a vertical WSe2 PV device with a high PCE of 5.44% under one-sun AM1.5G illumination. We reveal the multifunctional nature of a tungsten oxide layer, which promotes a stronger internal electric field by overcoming limitations imposed by the Fermi-level pinning at WSe2 interfaces and acts as an electron-selective contact in combination with monolayer graphene. Together with the developed bottom contact scheme, this simple yet effective contact engineering method improves the PCE by more than five times.

    View details for DOI 10.1021/acsnano.1c10054

    View details for PubMedID 35435652

  • High-specific-power flexible transition metal dichalcogenide solar cells. Nature communications Nassiri Nazif, K., Daus, A., Hong, J., Lee, N., Vaziri, S., Kumar, A., Nitta, F., Chen, M. E., Kananian, S., Islam, R., Kim, K., Park, J., Poon, A. S., Brongersma, M. L., Pop, E., Saraswat, K. C. 2021; 12 (1): 7034

    Abstract

    Semiconducting transition metal dichalcogenides (TMDs) are promising for flexible high-specific-power photovoltaics due to their ultrahigh optical absorption coefficients, desirable band gaps and self-passivated surfaces. However, challenges such as Fermi-level pinning at the metal contact-TMD interface and the inapplicability of traditional doping schemes have prevented most TMD solar cells from exceeding 2% power conversion efficiency (PCE). In addition, fabrication on flexible substrates tends to contaminate or damage TMD interfaces, further reducing performance. Here, we address these fundamental issues by employing: (1) transparent graphene contacts to mitigate Fermi-level pinning, (2) MoOx capping for doping, passivation and anti-reflection, and (3) a clean, non-damaging direct transfer method to realize devices on lightweight flexible polyimide substrates. These lead to record PCE of 5.1% and record specific power of 4.4Wg-1 for flexible TMD (WSe2) solar cells, the latter on par with prevailing thin-film solar technologies cadmium telluride, copper indium gallium selenide, amorphous silicon and III-Vs. We further project that TMD solar cells could achieve specific power up to 46Wg-1, creating unprecedented opportunities in a broad range of industries from aerospace to wearable and implantable electronics.

    View details for DOI 10.1038/s41467-021-27195-7

    View details for PubMedID 34887383

  • High-Performance p-n Junction Transition Metal Dichalcogenide Photovoltaic Cells Enabled by MoOx Doping and Passivation. Nano letters Nassiri Nazif, K., Kumar, A., Hong, J., Lee, N., Islam, R., McClellan, C. J., Karni, O., van de Groep, J., Heinz, T. F., Pop, E., Brongersma, M. L., Saraswat, K. C. 2021

    Abstract

    Layered semiconducting transition metal dichalcogenides (TMDs) are promising materials for high-specific-power photovoltaics due to their excellent optoelectronic properties. However, in practice, contacts to TMDs have poor charge carrier selectivity, while imperfect surfaces cause recombination, leading to a low open-circuit voltage (VOC) and therefore limited power conversion efficiency (PCE) in TMD photovoltaics. Here, we simultaneously address these fundamental issues with a simple MoOx (x 3) surface charge-transfer doping and passivation method, applying it to multilayer tungsten disulfide (WS2) Schottky-junction solar cells with initially near-zero VOC. Doping and passivation turn these into lateral p-n junction photovoltaic cells with a record VOC of 681 mV under AM 1.5G illumination, the highest among all p-n junction TMD solar cells with a practical design. The enhanced VOC also leads to record PCE in ultrathin (<90 nm) WS2 photovoltaics. This easily scalable doping and passivation scheme is expected to enable further advances in TMD electronics and optoelectronics.

    View details for DOI 10.1021/acs.nanolett.1c00015

    View details for PubMedID 33852295

  • Free-standing 2.7 mu m thick ultrathin crystalline silicon solar cell with efficiency above 12.0% NANO ENERGY Xue, M., Nazif, K., Lyu, Z., Jiang, J., Lu, C., Lee, N., Zang, K., Chen, Y., Zheng, T., Kamins, T., Brongersma, M. L., Saraswat, K. C., Harris, J. S. 2020; 70

    View details for DOI 10.1016/j.nanoen.2020.104466

    View details for Web of Science ID 000521052900040

  • Doped WS2 transistors with large on-off ratio and high on-current Kumar, A., Nazif, K., Ramesh, P., Saraswat, K., IEEE IEEE. 2020

    View details for Web of Science ID 000615719100013

  • Towards high V-oc, thin film, homojunction WS2 solar cells for energy harvesting applications Nazif, K., Kumar, A., de Menezes, M., Saraswat, K., Matin, M., Lange, A. P., Dutta, A. K. SPIE-INT SOC OPTICAL ENGINEERING. 2019

    View details for DOI 10.1117/12.2533007

    View details for Web of Science ID 000511164400001

  • Proposing a high-efficiency dielectrophoretic system for separation of dead and live cells SCIENTIA IRANICA Shayestehpour, H., Nazif, K., Soufi, A. M., Saidi, M. S. 2018; 25 (1): 186-195

    View details for DOI 10.24200/sci.2017.4502

    View details for Web of Science ID 000431953600002

  • Thermal Co-Design of Exascale Computing System in Packages (SiPs) Nazif, K., Kumari, N., Silverthorn, S., IEEE IEEE. 2018: 345-353

    View details for Web of Science ID 000467263000050

  • Si Heterojunction Solar Cells: A Simulation Study of the Design Issues IEEE Transactions on Electron Devices Islam, R., Nazif, K. N., Saraswat, K. C. 2016; 63 (12): 4788 - 4795

    View details for DOI 10.1109/TED.2016.2613057

  • Optimization of Selective Contacts in Si Heterojunction Photovoltaic Cells Considering Fermi Level Pinning and Interface Passivation Islam, R., Nazif, K., Saraswat, K., IEEE IEEE. 2016: 2440-2443

    View details for Web of Science ID 000399818702106