Fully Spray-Coated Triple-Cation Perovskite Solar Cells

Abstract

We use ultrasonic spray-coating to sequentially deposit thin films of tin oxide, a triple-cation perovskite and spiro-OMeTAD, allowing us fabricate perovskite solar cells (PSCs) with a champion reverse scan power conversion efficiency (PCE) of 19.4% on small-area substrates. We show that the use of spray-deposition permits us to rapidly (>80 mm s^-1) coat 25 mm × 75 mm substrates that were divided into a series of devices each with an active area of 15.4 mm², yielding an average PCE of 10.3% and a peak PCE of 16.3%. By connecting seven 15.4 mm² devices in parallel on a single substrate, we create a device having an effective active area of 1.08 cm² and a PCE of 12.7%. This work demonstrates the possibility for spray-coating to fabricate high efficiency and low-cost perovskite solar cells at speed.

Figure 1

Part (a) shows a photograph of small and large-area fully spray-coated perovskite solar cells. Parts (b,c) show a cross-sectional SEM image of complete devices incorporating a spray-cast perovskite layer. The device in part (b) utilises spin cast SnO₂ and spiro-OMeTAD layers whereas the device in part (c) is fully spray-coated.

Figure 2

Box plots showing reverse scan PSC performance recorded from small-area (2.5 mm²) devices A-D (see Table 1 for a description of device labels).

Figure 3

Topographical (panels a,c,e,g) and laser-beam-induced current mapping (panels b,d,f,h) images of spray-coated perovskite solar cells. See Table 1 for a description of device labels.

Figure 4

(a) Current-voltage characteristics for “champion” fully spray-cast perovskite solar cells with an active area of 2.5 mm² (small-area) and 15.4 mm² (large-area). The reverse scan PCE for these sweeps are 19.4% and 16.3% for the small and large-area cells respectively. (b) Output power of the champion devices when held (for 60 s) at a fixed voltage close to the maximum power point, indicating a stabilised PCE of 18.7% and 16.3% for small and large-area cells respectively. (c) A histogram of reverse-scan PCE data from 43 fully spray-cast small-area devices and 45 large-area devices.