David Needell1 Haley Bauser1 Megan Phelan1 Colton Bukowsky1 Ognjen Ilic1 Brent Koscher2 Junwen He3 Hanxiao Su3 Ralph Nuzzo3 A. Alivisatos2 Harry Atwater1

1, Applied Physics and Materials Science, California Institute of Technology, Pasadena, California, United States
2, Chemistry, University of California, Berkeley, Berkeley, California, United States
3, Chemistry, University of Illinois at Urbana-Champaign, Urbana-Champaign, Illinois, United States

Since the inception of the luminescent solar concentrator (LSC) in the early 1970s for photovoltaic (PV) applications, tremendous research efforts continue to be directed toward harnessing LSC technology for power generation in large-area windows. Future energy-efficient buildings will ideally be equipped with windows that (i) provide for daylighting, (ii) enable flexible choice of colors, including transparent, grey and RGB values, (iii) manage thermal radiation to improve thermal efficiency, (iv) generate significant quantities of electrical power, and (v) have costs equal to or less than double-glazed windows. While LSCs represent an intriguing approach for such building integrated applications, current LSC technology does not maintain performance when scaled to module sizes comparable to current window areas.

To address this issue of sustained power efficiency with increasing module area, we introduce a scalable LSC form factor by patterning a grid of micro-cell, Si PV cells embedded within a layer of PLMA doped with InAs/InP/ZnS quantum dots (QDs). By fixing the waveguide to PV area factor (i.e. geometric gain), we demonstrate consistent photon travel lengths with increasing module size. We apply both a Monte Carlo ray-trace algorithm and an analytical closed form calculation of such power window performance for an arbitrarily large area, and evaluate visible transparency of such a re-engineered LSC device for building integrated PV applications. Such planar grid architecture represents a significant departure from traditional LSC geometries, which align the PV collector along the perimeter of the waveguide. Our analysis reveals how a grid-pattern arrangement for LSCs permits scalability, high power conversion efficiency, and tailored transparency.