I recently attended SPIE’s Optics and Photonics conference, held every year in the beautiful San Diego Convention Center.  It was my second time attending the conference, having been there previously in 2013. This year I was lucky enough to receive funding to attend from the Photovoltaic Innovation Network.

I arrived in San Diego on a beautiful Sunday afternoon (although so far as I’ve been able to tell, there’s no such thing as a non-beautiful afternoon in San Diego). After checking into my hotel, I headed to the convention center to enjoy the opening talks of the conference. Upon arrival, however, I discovered that the registration and badge pickup counter had closed for the evening. Undeterred, I headed for the talks anyway, but was stopped by multiple conference volunteers. They informed me that I would need a badge to enter. This surprised me, as I wouldn’t have thought people sneaking in to physics conferences was a big problem (now people sneaking out, on the other hand – that I’m familiar with). In any case, not being one to rock the boat, I left without complaint and resigned myself to spending an evening exploring the city – which, as far as consolation prizes go, is really not too bad.

The next day I arrived at the convention center bright and early, determined to actually see some physics talks this time around. I picked up my badge without issue, and – now able to prove that I wasn’t just trying to learn for free – was granted access to the conference. Success! Being a solar researcher, my main priority was to see the latest and greatest research in the world of photovoltaics. In the morning I attended a session on light trapping in solar cells (which is the main focus of my research), and the afternoon featured some excellent plenary talks, with topics ranging from the current status of CdTe solar cells, to photochemical upconversion, to the importance of module reliability in creating truly viable solar power. After a poster session in the afternoon, Monday evening saw all the attendees gather together for a welcome reception, held on the beautiful convention center terrace.  The conference organizers had arranged for amateur astronomers to set up telescopes all around the terrace, and so I got a chance to see Saturn’s rings as well as Titan.

Tuesday brought with it many more interesting talks. A highlight was Yang Yang’s plenary talk on recent progress in organic and perovskite solar cells. In general there was a great deal of excitement surrounding perovskite solar cells at the conference. Of course, one nice aspect of attending a conference as large as Optics and Photonics is being able to go to talks outside one’s area of research. I took advantage of this opportunity and went to a wide variety of talks, including several fascinating presentations on exoplanet detection.

On Wednesday I went to a number of talks on organic and perovskite solar cells. One session was devoted to applications of nanophotonics, which directly pertained to my research. In my own work I do numerical simulations to show how photonic crystals (periodic arrangements of dielectric materials – see image below) can be used to increase light absorption in solar cells. The idea is that with a photonic crystal, you can “trap” the light, resulting in the cell absorbing almost all incoming photons with very little active material. This can lead to lower material costs and higher cell efficiencies. There were a number of interesting talks in this area of research. Akshit Peer gave a talk demonstrating that, in numerical simulations, the use of a dual photonic crystal architecture could increase light absorption by up to 50% in organic solar cells (relative to the usual planar cell architecture). This work was notable for making use of an architecture which could be relatively easy to fabricate – many proposed solar cell designs that make use of photonic crystals show excellent performance in simulations, but would be extremely difficult to manufacture in the real world. I’ll probably be rethinking what kinds of designs I should be studying as a result of this talk. Overall, most of the talks related to photonic crystal-based solar cells were based on numerical simulations, and the impression one got was that the field – while having no shortage of new and interesting ideas – is still largely waiting for fabrication technology to catch up to theory.

A few different photonic crystal architectures our group studies. On the left is a “slanted cone” geometry, which is particularly good at absorbing incident light, and hence very useful for solar cells.

On Wednesday afternoon there was another poster session, which featured much in the way of interesting research. The poster session also provided a great opportunity to interact with fellow students. I met several people from all corners of the world, and a few of us ended up going out for a few drinks that evening. Of course, being the somewhat uncoordinated person that I am, I managed to break my glasses before I went out. Still, I ended up having a very enjoyable (if somewhat blurry) night.

Thursday was the last day of the conference, and I wasn’t about to let a pair of broken glasses stop me from enjoying it. So, I pulled out my pair of prescription sunglasses and headed for the convention center. I probably got a few stares here and there for wearing sunglasses, especially in the darkened rooms where presentations were held, but I was unperturbed – it was all in the name of physics, after all. There were fewer talks related to my research on Thursday, and so I continued to seek out research that was outside my area of expertise. I went to one session in particular on the nature of light, entitled “What is a Photon?”. The talks for that session were – well, maybe a bit out there, but I was glad to see that there were still physicists willing to engage with foundational, philosophical, and interpretational questions.

After the conference ended Thursday afternoon, I spent a relaxing evening strolling around San Diego, and then was up bright and early Friday morning for my flight back to Toronto. Overall, I had a wonderful time in San Diego and learned a great deal from the conference. It was an excellent experience, and I’d like to thank PVIN for giving me the chance to attend!

Stephen Foster
PhD Candidate, University of Toronto