The Shockley-Queisser limit for nanostructured solar cells

TL;DR

This paper analyzes the theoretical efficiency limit of nanostructured solar cells, showing they can reach up to 42% efficiency under standard illumination, but do not surpass the Shockley-Queisser limit for concentrated sunlight.

Contribution

It demonstrates that nanostructured solar cells have a maximum efficiency of 42% and clarifies their potential and limitations relative to traditional photovoltaic devices.

Findings

Single-junction nanostructured cells reach 42% efficiency.

They do not exceed the Shockley-Queisser limit for concentrated sunlight.

Nanostructures enable built-in optical concentration.

Abstract

The Shockley-Queisser limit describes the maximum solar energy conversion efficiency achievable for a particular material and is the standard by which new photovoltaic technologies are compared. This limit is based on the principle of detailed balance, which equates the photon flux into a device to the particle flux (photons or electrons) out of that device. Nanostructured solar cells represent a new class of photovoltaic devices, and questions have been raised about whether or not they can exceed the Shockley-Queisser limit. Here we show that single-junction nanostructured solar cells have a theoretical maximum efficiency of 42% under AM 1.5 solar illumination. While this exceeds the efficiency of a non- concentrating planar device, it does not exceed the Shockley-Queisser limit for a planar device with optical concentration. We conclude that nanostructured solar cells offer an important route towards higher efficiency photovoltaic devices through a built-in optical concentration.