Elevated Stability and Efficiency of Solar Cells via Ordered Alloy Co-Acceptors

Abstract

Power conversion efficiency (PCE) and long-term stability are the two key parameters of photovoltaic devices to meet standards for commercial use. In this Letter, an ordered alloyed coacceptor by incorporating PC 61 BM and CO i 8DFIC is obtained. This ordered alloy structure increases the light absorption by producing a shoulder peak at 935 nm and improves electron mobility from 1.51 × 10 −5 to 8.91 × 10 −4 cm 2 V −1 s −1 by PC 61 BM interacting with the end group of CO i 8DFIC and connecting adjacent CO i 8DFIC molecules. Consequently, the PCE is enhanced from 10.80 to 14.22%, enhancement of about 32%. Even further, the device stability is improved due to the fact that the alloy fixes the morphology of the active layer. After keeping for 7200 h, about 10 months, the PCE of those solar cells is retained at 13.2%, corresponding to a PCE loss of only 5.7%, while the PCE loss in the binary control device is up to 33.3%.

Induced J-aggregation in acceptor alloy enhances photocurrent

“…According to our previous study, this peak originates from the J-aggregation of CO i 8DFIC [11]. Fullerene or nonfullerene molecules can promote the J-aggregation of CO i 8DFIC, thus broadening the absorption and EQE spectra [6,12,13]. CO i 10DFIC can induce the J-aggregation of CO i 8DFIC, as the absorption spectrum for CO i 10DFIC:CO i 8DFIC blend film can confirm this (Fig.…”

Asymmetric Acceptors with Fluorine and Chlorine Substitution for Organic Solar Cells toward 16.83% Efficiency

“…The development of organic solar cells (OSCs) has experienced a prosperous period in the past decade. [ 1–33 ] Due to their noticeable properties such as semi‐transparency, flexibility and environmental friendliness, the passion of commercialization from researchers and investors is always high. [ 34–38 ] At present, focusing on designing well performed “acceptor‐donor‐acceptor (A‐D‐A)”‐type small molecular acceptors (SMAs), especially the A‐DA'D‐A structured SMAs, is the mainstream of breaking through the bottleneck of power conversion efficiencies (PCEs), for their photovoltaic properties can be easily tuned by simple synthesis steps.…”

18% Efficiency organic solar cells

“…These nonfullerene acceptors have strong visible-NIR light-harvesting capability and good electron mobility, delivering higher short-circuit current density (J sc ) and PCE in solar cells than fullerene acceptors. To further enhance light absorption, Xiao et al [13][14][15][16][17][18][19][20][21][22][23][24][25][26] developed stronger light-harvesting A-D-A acceptors by using more electron-rich carbon-oxygenbridged (CO-bridged) core units. The acceptor CO i 8DFIC, based on an octacyclic CO-bridged unit, CO i 8, presents a narrow bandgap of 1.26 eV and strong absorption at 600-1000 nm [15].…”