Design of Near‐Infrared Nonfullerene Acceptor with Ultralow Nonradiative Voltage Loss for High‐Performance Semitransparent Ternary Organic Solar Cells

Abstract

Semitransparent organic solar cells (ST‐OSCs) are considered as one of the most valuable applications of OSCs and a strong contender in the market. However, the optical band gap of current high‐performance ST‐OSCs is still not low enough to achieve the optimal balance between power conversion efficiency (PCE) and average visible transmittance (AVT). An N‐substituted asymmetric nonfullerene acceptor SN with over 40 nm bathochromically shifted absorption compared to Y6 was designed and synthesized, based on which the device with PM6 as donor obtained a PCE of 14.3 %, accompanied with a nonradiative voltage loss as low as 0.15 eV. Meanwhile, ternary devices with the addition of SN into PM6 : Y6 can achieve a PCE of 17.5 % with an unchanged open‐circuit voltage and improved short‐circuit current. Benefiting from extended NIR absorption and lowered voltage loss, ST‐OSCs based on PM6 : SN : Y6 were fabricated and the optimized device demonstrated a PCE of 14.0 % at an AVT of 20.2 %, which is the highest PCE at an AVT over 20 %.

Process‐Aid Solid Engineering Triggers Delicately Modulation of Y‐Series Non‐Fullerene Acceptor for Efficient Organic Solar Cells

“…As illustrated in Figure 1g, there exists a dipole moment of 1.01 Debye in the neat Y6 molecule with 3D vector of x = 0, y = 1, z = 0, indicating the dipole direction is parallel to the plane direction of Y6 geometry. This observation is similar to the results reported by Zhu et al [38] After coupling the DBCl on top of Y6, the diploe moment remarkably increases to 1.93 Debye, with an improvement of 91.1% in comparison with that of neat Y6. More specifically, the dipole direction in the Y6:DBCl dimer shows a vector direction: x = 0.17, y = 0.67, z = −1.81 with an upward sloping orientation in comparison with that of Y6.…”

Photoinduced Charge Transfer and Recombination Dynamics in Star Nonfullerene Organic Solar Cells

“…First, decreasing the binding energy of the CT states (e.g., by changing the dielectric constant of BHJ film 25 ) and increasing the delocalization of CT states (e.g., by improving π−π stacking 37 ) can facilitate the dissociation of CT excitons and hinder the formation of CT states from charge carriers and thus the localized NFA triplet states. Second, enhancing the radiative QE of NFAs (e.g., by enhancing J aggregation 52 with higher dipole moment of NFA 53 ) can effectively reduce nonradiative recombination loss in small D/A energy offset OSCs systems. 10 Third, decreasing the energy difference between the NFA triplet state and CT state or increasing the hybridization of them is worth exploring to enable the back transfer of NFA triplet states to the CT state and thus charge carriers.…”

Recent advances of non‐fullerene organic solar cells: From materials and morphology to devices and applications

“…Currently, state-of-the-art singlejunction ST-OSCs exhibit the champion PCEs of 14% with an AVT over 20% and over 15% at an AVT closing 20%. 193,194 The record light utilization efficiency (LUE) of 5.35% is achieved, and 15.10% PCE is demonstrated at 25% AVT, via novel aperiodic band-pass filter (ABPF) transparent electrode with total reflection in the NIR region (700-900 nm). 195 This has led to the belief that the tandem strategy is expected to push the efficiencies of ST-OSCs toward 17%.…”