Perovskite Solar Cells
The light absorbing material, also described as photoactive material, in PSCs is based on an inorganic-organic metal halide compound that forms a “perovskite” crystal structure (Figure 1, left image). In a thin film PSC, the light absorbing perovskite layer is embedded within a multilayer stack of different functional materials that all perform different electroactive roles within the cell (Figure 1, right).
A perovskite crystal structure (left) and multi-layer configuration comprised in a perovskite solar cell showing main functional layers (right).
PSCs are unique as they can be solution processed, i.e. all materials can be deposited from solution without the use of vacuum, while retaining comparatively high power conversion efficiency (PCE) outcomes. The record efficiency of PSCs using a solution-processed absorber layer has rapidly climbed over the past decade, from 3.8% in 2009 to above 23% in 2019. However, the challenge remains to produce PSCs using scalable production methods that are translatable to industry while retaining the high PCEs we have seen in small scale cells. These small scale cells, while solution processed, are often fabricated using spin coating which is not easily scalable.
At CSIRO we employ a bottom-up approach – we use industry translatable printing and coating methods at all stages from our research, from 0.1 cm2 cells to our 30 cm wide reels. Along with partners Monash University, UNSW and the University of Cambridge, and thanks for funding from the Australian Renewable Energy Agency, we are scaling-up PSC production and countering challenges head-on. We have already demonstrated flexible PSCs with power conversion efficiencies of over 9%, processed at a very low energy cost using roll-to-roll fabrication. Our goal is to achieve 13% power conversion efficiencies of these cells in the next two years!
Roll-to-roll coating of perovskite in progress.