UC San Diego

Perovskite Solar Cell (PSC) technology has gained a lot of interest in the photovoltaics community due to their excellent opto-electronic properties. The inverted architecture (p-i-n) PSCs are especially promising from a commercialization point of view. Herein, we developed an automated deposition process for Electron Transport Layer (ETL) C60 and interfacial buffer layer BCP using a scalable deposition technique, physical vapor deposition (PVD), to establish a baseline for p-i-n devices based on a wide bandgap Perovskite composition. With the help of a Perovskite Automated Solar Cell Assembly Line (PASCAL) robot and with multiple iterations on devices, we were able to show reproducibility in the fabrication process of single-junction devices, which is typically one of the main advantages of adopting a scalable technique such as PVD. Additionally, devices showed reasonable performance, with a PCE of 17%, Voc of 1.02 V, and Jsc of 20 mA/cm2. To implement these devices into tandems, which require a transparent top cell and therefore a sputtered transparent conductive oxide top contact which necessitates a sputter buffer layer, we investigated PVD SnOx as a replacement ALD SnOx (difficult to commercialize). However, it was shown that the as-deposited SnOx isn’t dense enough to act as a protection layer, requiring an alternative buffer layer and/or alternate TCOs which have a soft-landing deposition process. Lastly, using implied Voc calculations, it is shown that much of the PSC performance is lost at the interfaces due to extensive non-radiative recombination. In this direction, a Lithium Fluoride buffer layer showed promising passivation effect at the PSK/ETL interface and could be the next step towards optimization.