Enabling low voltage losses and high photocurrent in fullerene-free organic photovoltaics

Abstract

Despite significant development recently, improving the power conversion efficiency of organic photovoltaics (OPVs) is still an ongoing challenge to overcome. One of the prerequisites to achieving this goal is to enable efficient charge separation and small voltage losses at the same time. In this work, a facile synthetic strategy is reported, where optoelectronic properties are delicately tuned by the introduction of electron-deficient-core-based fused structure into non-fullerene acceptors. Both devices exhibited a low voltage loss of 0.57 V and high short-circuit current density of 22.0 mA cm−2, resulting in high power conversion efficiencies of over 13.4%. These unconventional electron-deficient-core-based non-fullerene acceptors with near-infrared absorption lead to low non-radiative recombination losses in the resulting organic photovoltaics, contributing to a certified high power conversion efficiency of 12.6%.

Barrierless Free Charge Generation in the High‐Performance PM6:Y6 Bulk Heterojunction Non‐Fullerene Solar Cell

“…As a direct consequence, short‐circuit currents ( J SC ) over 25 mA cm −2 and open circuit voltages ( V OC ) above 0.8 V have been reported for different NFA blends . Notably, high J SC values have been shown for NFA‐based blends with moderate energy offsets at the donor–acceptor heterojunction . Low driving forces go along with reduced voltage losses, slightly above 0.5 V .…”

Understanding the Effect of the Third Component PC71BM on Nanoscale Morphology and Photovoltaic Properties of Ternary Organic Solar Cells

“…To better meet the requirements of the industrial commercialization, golden triangle of the OSCs including photovoltaic performance, cost, and device stability should be further considered . Recently, Yuan et al reported a series of novel A‐DA'D‐A‐type n‐OS acceptors based on the central fused ring inserted with benzotriazole or benzothiadiazole units, which displayed excellent photovoltaic performance with small energy loss . Generally, the difference of energy offset between the lowest unoccupied molecular orbital (LUMO) of acceptor and the highest occupied molecular orbital (HOMO) of donor critically determines the open circuit voltage ( V oc ) of OSCs.…”

H‐Bonds‐Assisted Molecular Order Manipulation of Nonfullerene Acceptors for Efficient Nonannealed Organic Solar Cells

“…To further investigate the universality of the IT‐DOH as acceptor, we fabricated OSCs based on another widely used donor polymer PM6 without the TA, yielding a best PCE of 12.5% (Figure b, Table ). It is worth noting that the E loss of these devices was calculated to be about 0.57 eV, which is quite low among those reported with such high efficiencies . The AFM and 2D GIXD (Figure S7, Supporting Information) were also measured to study the PM6:IT‐DOH blend film, which presented good morphology and face‐on orientation, similar to those of the PBDB‐T:IT‐DOH blend film.…”