Tin Oxide Electron Transport Layers for Air-/Solution-Processed Conventional Organic Solar Cells

Abstract

Commercialization of organic solar cells (OSC) is imminent. Interlayers between the photoactive film and the electrodes are critical for high device efficiency and stability. Here, the applicability of SnO 2 nanoparticles (SnO 2 NPs) as the electron transport layer (ETL) in conventional OSCs is evaluated. A commercial SnO 2 NPs solution in butanol is mixed with ethanol (EtOH) as a processing co-solvent to improve film formation for spin and slot-die coating deposition procedures. When processed with 200% v/v EtOH, the SnO 2 NPs film presents uniform film quality and low photoactive layer degradation. The optimized SnO 2 NPs ink is coated, in air, on top of two polymer:fullerene-based systems and a nonfullerene system, to form an efficient ETL film. In every case, addition of SnO 2 NPs film significantly enhances photovoltaic performance, from 3.4 and 3.7% without the ETL to 6.0 and 5.7% when coated on top of PBDB-T:PC 61 BM and PPDT2FBT:PC 61 BM, respectively, and from 3.7 to 7.1% when applied on top of the PTQ10:IDIC system. Flexible, all slot-die-coated devices, in air, are also fabricated and tested, demonstrating the versatility of the SnO 2 NPs ink for efficient ETL formation on top of organic photoactive layers, processed under ambient condition, ideal for practical large-scale production of OSCs.

Unprecedented Efficiency Increase in a Ternary Polymer Solar Cell Exhibiting Polymer-Mediated Polymorphism of a Non-Fullerene Acceptor

“…For reference, Welch et al reported a V oc of 0.52 V and PCE of 3.4% when fabricating the PTQ10:IDIC binary cells with a conventional architecture and measuring in air. 43 In addition, we measured binary blend solar cells of PTQ10:IDID and IDID:PC 61 BM as controls and the results are shown in Table S2. IDID:PC 61 BM showed no measurable photovoltaic effect, possibly due to the inability to generate a uniform film.…”

Recent progress in solution-processed flexible organic photovoltaics

“…It is noteworthy that the efficiency of the devices remained at 12% with a 530 nm thick blade-coated SnO 2 layer. Recently, Hoff et al successfully deposited SnO 2 nanoparticles (NPs) on top of the active layers in air by slot-die coating 133 . Ethanol was added to a commercial SnO 2 solution to improve the film quality.…”

An Alcohol‐Soluble N‐Annulated Perylene Diimide Cathode Interlayer for Air‐Processed, Slot‐Die Coated Organic Photovoltaic Devices and Large‐Area Modules

“…[8,13] For large-area applications that are compatible with roll-to-roll fabrication techniques, CILs are required to be air stable and allow uniform film formation from solvents that are immiscible with that of the photoactive layers. [10,[14][15][16] However, critical challenges persist regarding the synthesis and processing of suitable CILs that can be applied to upscaled devices and modules. Amino-containing conjugated polymers such as polyethyleneimine ethoxylated (PEIE) and polyfluorene (PFN and PFN-Br) have been adopted as CILs to deliver high-performance OPVs due to suitable film formation from solvents immiscible with photoactive layers (e.g., water and alcohols) and an ability to facilitate electron transfer to electrodes.…”

“…[ 8,13 ] For large‐area applications that are compatible with roll‐to‐roll fabrication techniques, CILs are required to be air stable and allow uniform film formation from solvents that are immiscible with that of the photoactive layers. [ 10,14–16 ] However, critical challenges persist regarding the synthesis and processing of suitable CILs that can be applied to upscaled devices and modules.…”