An n‐n Heterojunction Configuration for Efficient Electron Transport in Organic Photovoltaic Devices

Abstract

Selective electron transport and extraction are essential to the operation of photovoltaic devices. Electron transport layer (ETL) is therefore critical to organic photovoltaics (OPV). Herein, an ETL configuration is presented comprising a solution‐processed n‐n organic heterojunction to enhance electron transport and hole blocking, and boost power conversion efficiency (PCE) in OPV. Specifically, the n‐n heterojunction is constructed by stacking a narrow‐band n‐type conjugated polymer layer (PNDIT‐F3N) and a wide‐band n‐type conjugated molecule layer (Phen‐NaDPO). Based on the ultraviolet photoelectron spectroscopy measurement and numerical simulation of current density‐voltage characteristics, the formation of the built‐in potential is investigated. In three OPVs with different active layers, substantial improvements are observed in performance following the introduction of this ETL configuration. The performance enhancement arises from the combination of selective carrier transport properties and reduced recombination. Another contributing factor is the good film‐forming quality of the new ETL configuration, where the surface energies of the related materials are well‐matched. The n‐n organic heterojunction represents a viable and promising ETL construction strategy for efficient OPV devices.

Construction of TiO2–x Confined by Layered Iron Silicate toward Efficient Visible-Light-Driven Photocatalysis–Fenton Synergistic Removal of Organic Pollutants

“…The levels of CB and VB edge of FeMMT and TiO 2– x match the band edge levels of the type I heterojunction. Combined with the above analysis results, the TiO 2– x /FeMMT composites could be constructed as an effective type I n–n heterojunction (Figure i), enabling effective separation and transfer of photogenerated electrons and holes. , α ( h v ) = A ( h v − E g ) 1 / 2 E V B = E C B + E g …”

Recent Progress of All Polymer Solar Cells with Efficiency Over 15%

“…Meanwhile, the WSCPs can be processed from orthogonal solvent, avoiding solvent erosion to the active layers during spin coating. Wu et al [ 54 ] reported two NDIs‐based WSCPs: PNDIT‐F3N and PNDIT‐F3N‐Br, which have been commonly used as CMLs benefiting from their high electron mobility and appropriate energy level. For example, PNDIT‐F3N was used as the CML in PM6:PY‐82:PY‐DT ternary system, achieving a high PCE of 18.03% for APSCs.…”

Double‐Dipole Induced by Incorporating Nitrogen‐Bromine Hybrid Cathode Interlayers Leads to Suppressed Current Leakage and Enhanced Charge Extraction in Non‐Fullerene Organic Solar Cells

“…Consequently, a PCE of 17.2% was obtained from the OSCs composed of PM6:Y6 with PDINN as the cathode interlayer. [ 17 ] PDI‐NO was synthesized as a cathode interlayer in indoor OSCs to facilitate charge extraction with lower charge carrier density. Owing to its deeper highest occupied molecular orbital level, PDI‐NO exhibited better hole‐blocking properties, leading to significantly lower leakage current and trap‐assisted recombination.…”

“…The enhanced performance was ascribed to the good film‐forming quality, combination of selective carrier transport properties, and reduced recombination. [ 17 ] Besides, the variety of PNDIT‐F3N and PDINN was reported and used in the OSCs composed of PM6:Y6. Compared with the OSCs with PNDIT‐F3N, the PCE of the OSCs with hybrid cathode interlayer attained a 7.76% increase, [ 23 ] resulting from enhanced charge extraction, better charge selectivity, and suppressed exciton recombination.…”