Nonhalogenated Solvent-Processed Fullerene-Free Ambient Stable Organic Solar Cells: Impact of Molecular Weight of New π-Conjugated Donor Polymer on Efficiency

Abstract

Environmentally benign solvent-processed photoactive materials are urgently required to replace the current toxic solvent processing, especially for nonfullerene organic solar cells (NFOSCs). In this regard, we report an efficient new π-conjugated polymer (P1) for high performance NFOSCs. The careful choice of side chain, number-average molecular weight (M n) tuning (low, medium, and high M n, denoted as P12, P19, and P32), and dedicated device engineering of NFOSCs resulted an impressive device performance. Interestingly, P19-based NFOSCs achieved a high power conversion efficiency (PCE) of over 10% with nonhalogenated solvents, which is much superior than the P12- and P32-based NFOSCs. The high performance of P1-M-M n polymer is very well correlated with its high short-circuit current density and fill factor values attained via well-defined active layer morphology. Moreover, the energy losses of the optimized devices are lower, which is very well correlated with the high V oc of the NFOSCs. Additionally, the ambient stability of the NFOSCS processed from nonhalogenated solvents is relatively higher than halogenated solvents because of the better morphological stability of nonhalogenated processed films. Overall, our study provides deep insight on M n impact on nonhalogenated processing and thereby efficiency enhancement in environmentally sustainable NFOSCs.

Nonhalogenated Solvent‐Processed Thick‐Film Ternary Nonfullerene Organic Solar Cells with Power Conversion Efficiency >13% Enabled by a New Wide‐Bandgap Polymer

“…The obtained Nyquist plot is shown in Figure 3c, fitted by the equivalent circuit. [ 29 ] The NFOSCs processed using P2:IT‐4F, P2:IT‐4F:BTP‐4F, and P2:IT‐4F:BTP‐4Cl exhibited bulk resistances of 1388.39, 937.16, and 728.86 Ω, respectively. The results are in good agreement with the J sc and FF values.…”

“…[ 26,27 ] Therefore, to satisfy the film morphology and device performance requirements using nonhalogenated solvents, we should analyze the compatibilities of π‐conjugated donor polymers and nonfullerene acceptors (NFAs) with nonhalogenated solvents. [ 28–30 ] However, few studies have addressed this aspect of NFOSCs. Hong et al reported a PCE > 15% when BTP‐4F was blended with modified alkyl chains blended with PBDB‐TF to produce a 100 nm active layer.…”

All-Polymer Solar Cells Approaching 12% Efficiency with a New π-Conjugated Polymer Donor Enabled by a Nonhalogenated Solvent Process

“…The new polymer donor Nap-SiBTz was synthesized by Stille polymerization (Scheme S2). , The detailed procedure used to synthesize Nap-SiBTz is described in Section and the Supporting Information. The structures of the new comonomer and Nap-SiBTz were confirmed by 1 H and 13 C NMR spectroscopies (Supporting Information).…”

Hot Hydrocarbon‐Solvent Slot‐Die Coating Enables High‐Efficiency Organic Solar Cells with Temperature‐Dependent Aggregation Behavior

“…Organic solar cells (OSCs) technology is regarded as one of the most promising sustainable and green energy sources for their promise as environmentally friendly and easily printable devices. [ 1–6 ] In recent years, bulk‐heterojunction (BHJ) OSCs have made impressive strides in their power conversion efficiency (PCE) owing to novel material synthesis, morphology optimization and device engineering, [ 7–15 ] resulting in PCE of single‐junction devices over 18%. [ 16 ] However, most of the devices with cutting‐edge performance were fabricated by spin‐coating using highly toxic halogenated solvents under controlled conditions, which is not favorable to the large‐scale commercialization of OSCs.…”