Potassium Thiocyanate‐Assisted Enhancement of Slot‐Die‐Coated Perovskite Films for High‐Performance Solar Cells

Stefaan De Wolf,Wenzhu Liu,Jingxuan Kang,Michele De Bastiani,Fuzong Xu,Furkan H Isikgor,Jiang Liu,George T Harrison,Erkan Aydin,Anand S Subbiah,Xinbo Yang

doi:10.1002/smsc.202000044

Stefaan De Wolf, Wenzhu Liu + Show 9 more

Open Access

https://doi.org/10.1002/smsc.202000044

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Abstract

Slot‐die coating is highly promising for scaled deposition of metal halide perovskite thin films. However, the power conversion efficiencies (PCEs) of slot‐die‐prepared perovskite solar cells (PSCs) still lag behind their spin‐casted counterparts. To resolve this issue, the crystal size and quality of slot‐die‐coated methylammonium lead triiodide (MAPbI3) perovskite films are dramatically improved via additive engineering using potassium thiocyanate (KSCN). The modified micrometer‐thick films have an average grain size of ≈11 μm and charge‐carrier parameters that are comparable with single‐crystal perovskites, such as a 1.89 μs lifetime, 136.65 ± 31.52 cm2 V−1 s−1 mobility, and 25.15 ± 3.55 μm diffusion length. Exploiting these enhanced properties, planar inverted PSCs with negligible hysteresis are fabricated and an average and a maximum PCE of 20.14% and 21.38%, respectively, are achieved which are among the highest reported values for slot‐die‐coated PSCs. Notably, our devices have a narrow PCE distribution along the slot‐die coating axis, highlighting slot‐die coating's promise to fabricate large‐scale, high‐performance PSCs.

Highlights

In recent years, the record power conversion efficiency (PCE) ofThese imperfections are detrimental to the optoelectronic properties and stability of perovskite films, and impair the performance of PSCs.[23,24,25] to enable lab-scale perovskite solar cells (PSCs) has rapidly increased high-performance devices using high-throughput methods, to 25.5%.[1]
We find that the KSCN additive enlarges the grains significantly and reduces defect densities, thereby enabling slot-die-coated MAPbI3 films with long carrier diffusion lengths (25.15 Æ 3.55 μm)
Chemical reactions triggered by the KSCN additive during perovskite film formation are evident from X-ray photoelectron spectroscopy (XPS) (Figure 1a) and X-ray diffraction (XRD) (Figure 1b) results

Summary

Introduction

The record power conversion efficiency (PCE) of. These imperfections are detrimental to the optoelectronic properties and stability of perovskite films, and impair the performance of PSCs.[23,24,25] to enable lab-scale perovskite solar cells (PSCs) has rapidly increased high-performance devices using high-throughput methods, to 25.5%.[1] currently, the perovskite films used in deposition of perovskite layers with large grains (and minimal such high-performance devices are usually deposited by spin grain boundaries in the transverse direction), as well as fewer coating, which might not be suitable for square-meter scale defects, is of critical importance. To lower the processing temperature, aimed at protecting the underlying poly(triaryl amine) (PTAA) hole transport layer, we use in this work the methylamine (MA)/

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