Reduced bimolecular recombination in blade-coated, high-efficiency, small-molecule solar cells

Abstract

To realize the full promise of solution deposited photovoltaic devices requires processes compatible with high-speed manufacturing. We report the performance and morphology of blade-coated bulk heterojunction devices based on the small molecule donor p-DTS(FBTTh2)2 when treated with a post-deposition solvent vapor annealing (SVA) process. SVA with tetrahydrofuran improves the device performance of blade-coated films more than solvent additive processing (SA) with 1,8-diiodooctane. In spin-coating, SA and SVA achieve similar device performance. Our optimized, blade coated, SVA devices achieve power conversion efficiencies over 8 % and maintain high efficiencies in films up to ≈ 250 nm thickness, providing valuable resilience to small process variations in high-speed manufacturing. Using impedance spectroscopy, we show that this advantageous behavior originates from highly suppressed bimolecular recombination in the SVA-treated films. Electron microscopy and grazing-incidence X-ray scattering experiments show that SA and SVA both produce highly crystalline donor domains, but SVA films have a radically smaller domain size compared to SA films. We attribute the different behavior to variations in initial nucleation density and relative ability of SVA and SA to control subsequent crystal growth.

Nucleation and crystal growth control for scalable solution-processed organic–inorganic hybrid perovskite solar cells

“…8a) is a widely used scalable solution-coating technique in the printing industry, particularly in the initial testing of ink coatings. In printable electronics, initially, it has been widely applied for optoelectronic material deposition, such as organic thin-lm transistors (OTFTs), 136,137 organic light-emitting diodes (OLEDs), 138,139 organic solar cells (OSCs), 140,141 etc. In the blade coating deposition technique, a blade is applied to spread the loaded precursor solution along a moving substrate to form wet solution lms.…”

Effective Exciton Dissociation and Reduced Charge Recombination in Thick‐Film Organic Solar Cells via Incorporation of Insulating Polypropylene

“…Bulk‐heterojunction (BHJ) organic solar cells (OSCs) as a potential renewable energy have attracted a considerable attention over the past decades, as they offer the advantages of light weight, simple fabrication process, and semitransparency . Recently, the single‐junction OSCs that consisted of donor and acceptor have shown the best power conversion efficiency (PCE) of over 16% .…”

Recent Progress of Organic Solar Cells with Insulating Polymers

“…Organic solar cells (OSCs) are attracting considerable attention due to the advantages of light weight, semitransparency, and roll‐to‐roll production. [ 1–8 ] So far, a power conversion efficiency (PCE) of over 18% has been reported for single‐junction OSCs. [ 9,10 ] However, there is large room for improvement in the PCE due to the Shockley–Queisser theoretical limit of 33%.…”