2022 journal article

Low Voltage‐Loss Organic Solar Cells Light the Way for Efficient Semitransparent Photovoltaics

Solar RRL.

By: B. Luginbuhl*, S. Ko*, N. Ran*, H. Hu n, S. Becwar*, A. Karki*, M. Seifrid*, T. Okubo* ...

co-author countries: China 🇨🇳 France 🇫🇷 Japan 🇯🇵 United States of America 🇺🇸
author keywords: non-fullerene acceptors; non-fullerene organic solar cells; organic solar cells; recombination; semitransparent solar cells; solid-state NMR; voltage losses
Source: ORCID
Added: March 17, 2022

Organic solar cells that are transparent to visible light are highly desirable for applications such as window treatments or solar greenhouse panels. A key challenge is to simultaneously transmit most photons between 400 and 700 nm while retaining a high short‐circuit current and power conversion efficiency (PCE). Here, organic bulk heterojunction (BHJ) solar cells consisting of a donor polymer (PM2) is reported and the non‐fullerene acceptor ITIC‐Th achieves a PCE of 9.3%, and the BHJ thin films exhibit an average visible transmittance over 40%. This value is achieved primarily due to a very high open‐circuit voltage ( V OC ) of 0.93 V, which represents a voltage loss of only 0.50 V relative to the material optical bandgap, E opt . In PM2:PC 61 BM devices, this voltage loss increases to 0.62 V ( V OC = 0.82 V). It is found that this difference in V OC is due to higher nonradiative recombination in the fullerene‐based solar cell, suggesting that non‐fullerene acceptors may lead to better performance in semi‐transparent devices. The optoelectronic properties associated with PM2:ITIC‐Th and PM2:PC 61 BM blends are further corroborated by different morphological features and local structures at the donor‐acceptor interfaces characterized by atomic force microscopy, X‐ray scattering, and solid‐state NMR spectroscopy techniques.