Ultrafast Charge Carrier Dynamics at the Interface of p-n Semiconductor Heterojunctions (08/12/23)

Speaker and Affliation:

Prof. Hirendra Nath Ghosh
Director, National Institute of Science Education and Research (NISER) Bhubaneshwar, India.


8th December, 2023 (Friday), 4.00 PM (India Standard Time)


K I Vasu Auditorium, Dept. of Materials Engineering, IISc, Bangalore


Metal chalcogenides are the potential competitors to traditional crystalline silicon solar cells owing to their unique properties such as high abundance, high absorption coefficients (104 -105 cm-1), tunable bandgap, cost-effectiveness, and robust stability. However, their performance is constrained by challenges such as rapid recombination of photogenerated electron-hole pairs and inadequate band edge potentials. To address these limitations, p-n heterojunctions, where a high-bandgap n-type semiconductor is combined with a low-bandgap p-type semiconductor, have emerged as a highly promising approach. This approach facilitates the creation of reliable and efficient photonic devices capable of harnessing a broader spectrum of solar radiation. These junctions serve as the main active sites for efficient charge transfer processes, ensuring rapid separation and migration of photoinduced charge carriers due to the built-in electric field. Furthermore, to gain a comprehensive understanding of the optical and material properties of these heterojunction systems, it is imperative to investigate the ultrafast processes involved such as charge transfer, trapping, and relaxation dynamics of photogenerated electrons and holes. To this end, femtosecond transient absorption spectroscopy has been employed as a valuable tool. We have investigated the charge transfer dynamics at the interface of p-type copper, antimony, tin chalcogenides (Cu2ZnSnX4, CuX, SnX, Sb2X3, CuInX2: X=S, Se,) and n-type cadmium chalcogenides (CdX, X=S, Se) which is widely used in solar cell technology and photocatalysis. By probing into these ultrafast processes, research efforts aim to unlock opportunities for the development of highly efficient photovoltaic and photocatalytic devices, thereby contributing to the mitigation of energy and environmental challenges.

References (1) Kaur, A.; Goswami, T.; Babu, K. J.; Ghorai, N.; Kaur, G.; Shukla, A.; Rondiya, S. R.; J. Phys. Chem. C 2020, 124, 19476-19483. (2) Kaur, A.; Goswami, T.; Rondiya, S. R.; Jadhav, Y. A.; Babu, K. J.; Shukla, A.; Yadav, D. K.; Ghosh, H. N. J. Phys. Chem. Lett. 2021, 12, 10958-10968. (3) Ghorai, N.; Sachdeva, M.; Kharbanda, N.; Ghosh, H. N. ACS Photonics 2023, 10, 733-742. (4) Kaur, A.; Goswami, T.; Babu, K. J.; Shukla, A.; Bhatt, H.; Ghosh, H. N. J. Phys. Chem. Lett. 2022, 13, 11354-11362. (5) Kaur, A.; Goswami, T.; Babu, K. J.; Ghosh, H. N. J. Phys. Chem. Lett. 2023, 14, 7483-7489.


Prof. Ghosh brings over three decades of experience in semiconductor materials and femto-second ultrafast transient spectroscopy. He is a highly decorated senior professor and has made significant contributions to the field. Prof. Ghosh has established cutting-edge femto-second ultrafast transient spectroscopy facilities at renowned institutes such as Bhabha Atomic Research Center (BARC), Mumbai, and The Institute of Nano Science and Technology (INST), Mohali. Moreover, he has trained more than 25 PhD students in advanced experimental techniques. Prof Ghosh has been a recipient of various prestigious awards such as Sir J.C. Bose National Fellowship and is a fellow of almost all the National Academies of INDIA including both Science and Engineering. He also serves as the member of Advisory Editorial Board for various important ACS journals such as the Journal of Physical Chemistry Letters, Journal of Physical Chemistry C, etc.