Intrinsically Stretchable Organic Solar Cells beyond 10% Power Conversion Efficiency Enabled by Transfer Printing Method

Abstract

Stretchable organic solar cells (OSCs) simultaneously possessing high-efficiency and robust mechanical properties are ideal power generators for the emerging wearable and portable electronics. Herein, after incorporating a low amount of trimethylsiloxy terminated polydimethylsiloxane (PDMS) additive, the intrinsic stretchability of PTB7-Th:IEICO-4F bulk heterojunction (BHJ) film is greatly improved from 5% to 20% strain without sacrificing the photovoltaic performance. The intimate multi-layers stacking of OSCs is also realized with the transfer printing method assisted by electrical adhesive "glue" D-Sorbitol. The resultant devices with 84% electrode transmittance exhibit a remarkable power conversion efficiency (PCE) of 10.1%, which is among the highest efficiency for intrinsically stretchable OSCs to date. The stretchable OSCs also demonstrate the ultra-flexibility, stretchability, and mechanical robustness, which keep the PCE almost unchanged at small bending radium of 2 mm for 300 times bending cycles and retain 86.7% PCE under tensile strain as large as 20% for the devices with 70% electrode transmittance. The results provide a universal method to fabricate highly efficient intrinsically stretchable OSCs.

Intrinsically Stretchable Organic Solar Cells with Simultaneously Improved Mechanical Robustness and Morphological Stability Enabled by a Universal Crosslinking Strategy

“…We hypothesize that the strain‐induced sliding between active layer and the electrode is responsible for the deterioration of the device performance. [ 23 ]…”

“…[ 19,22 ] Our group introduced the flexible PDMS segments serving as plasticizer to enhance the mechanical endurance of active layer. [ 23 ] Besides insulating component, the third semiconducting materials (either donor or acceptor) have also been incorporated into the active layer (also namely ternary strategy). The PC 71 BM or polymer acceptor (P(NDI2OD‐T2)) can be blended in active layer to simultaneously increase its PCE and stretchability.…”

“…[19,22] Our group introduced the flexible PDMS segments serving as plasticizer to enhance the mechanical endurance of active layer. [23] Developing intrinsically stretchable organic solar cells (OSCs) with excellent mechanical robustness and long-term operation stability is highly demanded for practical applications. Here, the representative PM6/Y6 active layer film, crosslinked by a photo-crosslinkable small molecule 2,6-bis(4azidobenzylidene)cyclohexanone (BAC) containing azide groups, exhibits a significantly enhanced stretchability of 18% and toughness of 6.94 MJ m −3 , compared to non-crosslinked film (stretchability of 4.5% and toughness of 0.75 MJ m −3 ).…”

Recent Advances of Film–Forming Kinetics in Organic Solar Cells

“…Shao and co-workers reported using a PTB7-th:IEIC-4F blend system to study the effect of additives on morphology when PET/ITO, which is a stretchable substrate, was employed [119]. When 5 wt% PDMS was added to the blend with PET/ITO, compared to the PCE of 10.8% in the glass substrate system without additive, the PCE can be maintained at 10.3%, and did not deteriorate the phase separation structure of the BHJ layer (Figure 17a-d).…”

“…The morphology optimization of the nonfullerene-based blend films empirica Reprinted with permission from ref. [119]. Copyright 2021 Wiley.…”