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Dr. Peter Ho
Dr. Peter Ho Dr. Peter Ho received his PhD from University of Cambridge in 2001 (thesis advisor, Professor Richard Friend). He returned to Department of Physics, National University of Singapore in 2004, and set up an integrated research laboratory (ONDL) to investigate the science and technology of polymer organic semiconductors. On 2014, he appointed as the Vice Dean (Research), Faculty of Science, and then Deputy Dean since 2017.

Biography

Peter Ho, born in Singapore in 1971, received his PhD from University of Cambridge in 2001 (thesis advisor, Professor Richard Friend) for work on polymer organic semiconductor devices. He subsequently won a junior Research Fellowship from St John’s College, Cambridge, during which tenure he also moved to Bell Laboratories, New Jersey, as visiting scientist.  He returned to Department of Physics, National University of Singapore in 2004, and set up an integrated research laboratory (ONDL) to investigate the science and technology of polymer organic semiconductors together with Lay-Lay Chua, who later joined Department of Chemistry. Innovations from this laboratory include: generalized n-type organic field-effect transistors (2005), printable low-temperature nano-metal inks (2007), semiconductor-grade photocrosslinkers and morphology-stabilized devices (2010, 2012), broadband optical limiting formulations (2011), self-release 2D material transfer technique (2013), and self-compensated doped polymers with ultrahigh and ultrahigh work functions (2016–2017).  Peter’s research seeks to leverage these developments to gain insights into the physics and design of solution-processed devices, including organic light-emitting diodes, transistors, solar cells, and graphene–organic hybrids.


Peter has published over 80 articles in international journals, and is named inventor on over 20 patent families.  He was named Top Outstanding Young Person (Academic Leadership) by the Junior Chamber of Commerce, Singapore in 2009, and appointed Vice Dean (Research), Faculty of Science, 2014–2017, and then Deputy Dean since 2017.

All sessions by Dr. Peter Ho

  • Day 2Monday, February 26th
Conference
4:20 pm

Physics of contacts to organic solar cells

The rapid rise in performance of organic solar cells over the last decade derived in large part from advances in materials chemistry and processing morphology control of the donor–acceptor photoactive active layers. As a consequence, much of the work in device physics of organic solar cells has focused on the fundamental limits imposed by the photoactive layer, assuming that contacts are non-limiting through the use of MoOx and ZnO2 as hole- and electron-collection layers, with sufficiently high and low work functions, respectively. However, even so, contacts still do limit the performance of organic solar cells.

In this talk, I will explain recent work that shows how device energy-level alignment leads to inevitable losses that limit open-circuit voltage, fill factor, short-circuit current density and thus power conversion efficiency, and how contact behavior transits from the under-optimized regime to optimal to the over-optimized regime as the effective workfunction is swept across the Fermi-level pinning threshold, revealing an unexpected barrier to carrier extraction. As a consequence, there is still a lot of room to improve solar cell performance significantly by contacts engineering, especially in the development of technologically viable contacts, such as those formed by solution processing. I will demonstrate what can now be achieved in this space based on the self-compensated doped polymer charge-collection layers with ultrahigh and ultralow work functions.

Auditorium between Building 4 and 5 16:20 - 16:50 Details