Autonomous self-healing supramolecular polymer transistors for skin electronics

Skin-like field-effect transistors are key elements of bio-integrated devices for future user-interactive electronic-skin applications. Despite recent rapid developments in skin-like stretchable transistors, imparting self-healing ability while maintaining necessary electrical performance to these transistors remains a challenge. Herein, we describe a stretchable polymer transistor capable of autonomous self-healing. The active material consists of a blend of an electrically insulating supramolecular polymer with either semiconducting polymers or vapor-deposited metal nanoclusters. A key feature is to employ the same supramolecular self-healing polymer matrix for all active layers, i.e., conductor/semiconductor/dielectric layers, in the skin-like transistor. This provides adhesion and intimate contact between layers, which facilitates effective charge injection and transport under strain after self-healing. Finally, we fabricate skin-like self-healing circuits, including NAND and NOR gates and inverters, both of which are critical components of arithmetic logic units. This work greatly advances practical self-healing skin electronics.


Introduction
Skin-inspired thin-lm eld-effect transistors are core elements of integrated circuits for electronic skin to integrate with the human body.They have rapidly advanced the development of stretchable electronic materials [1][2][3] .They have demonstrated strong potential for applications in health monitoring, prosthetic sensory skin, medical implants, and brain-computer interface 4,5 .Despite substantial progresses of the above devices, studies on self-healing ability that is critical for skin-like devices when subjected to unexpected mechanical damages remains lacking 6 .
Intrinsically self-healing insulating materials have been developed with supramolecular polymer chemistry and are capable of reconstruction through dynamic intermolecular interactions [7][8][9] .However, for electronic materials, most self-healing polymers reported to date are electrically insulating, which limits their applications in functional self-healing transistors 10 .Thus, self-healing semiconductors and electrodes are ideal for skin-inspired transistor applications 6,11-13 .Self-healing conductors have been developed using composite materials with conducting nano llers, such as carbon materials and metal nanowires or liquid metals [14][15][16][17][18][19] .However, self-healing semiconductors are less developed.In addition, the above materials have yet been thoroughly investigated for use in self-healing eld-effect transistors.
Consequently, realizing fully autonomous self-healing transistors have the following ve major challenges 20 : (i) low elasticity of the self-healing semiconductor that induces fatigue failure, (ii) nonautonomous healing process involving heat and solvent treatments are unfavorable for practical applications, (iii) di cult to align limited healing area (submicron scale), (iv) strain-sensitive electrical properties preventing stable electrical characteristics, and (v) absence of suitable self-healing electrode and dielectric materials for both e cient current injection and a low operating voltage of the transistors 11- 13,21-23 .In this work, we address these challenges by introducing a supramolecular polymer transistor consisting of identical supramolecular self-healing polymers in conductor, semiconductor, and dielectric 23,24 .Such transistors can autonomously self-heal of micron-scale damage (up to 4 μm) in transistor con guration at ambient conditions and operate at a low drain voltage (−1 V).Using our selfhealing transistors, we proceed to fabricate an active-matrix array and logic gates.Their performance was maintained even when subjected to 30% biaxial strain.This work represents the rst report of an autonomously self-healing integrated logic circuit, showing the potential to incorporate stretchable selfhealing functions into future, more complex skin electronics.
The blended semiconductor lm was observed to have a nanoweb-like network of the semiconducting polymer that provides geometrical stretchability, while maintaining current ow pathways with high interconnectivity within the semiconducting polymer phase (Fig. 1b(i) and Fig. 1b(ii)).The observed nanoweb morphology in the SHE matrix was a result of phase separation due to the difference in surface energy between the materials (Supplementary Fig. 1). Figure 1b(iii) shows the Derjaguin-Muller-Toporov (DMT) modulus mapping image of the semiconductor lm, which indicates that the nanoweb network is composed primarily of the semiconducting polymer (DPPT-TT: 10 2 MPa level, SHE: 10 1 MPa).The percolating pathways for current transport in the semiconducting nanoweb were con rmed using conductive AFM (C-AFM) (Fig. 1b(iv)).The weight ratio of DPPT-TT to SHE was varied to control the Young's modulus and the crack onset strain of the blend lms (refer to details in Supplementary Note 2).A tradeoff relationship was observed between these two factors (Fig. 1c).The elastic modulus dramatically decreased and the crack onset strain substantially increased when the DPPT-TT:SHE weight ratio of the blend lm was 3:7 (Fig. 1c and Supplementary Figs.2-4).This ratio was also observed as a transitional point for the mechanical and electrical properties of the blended lm (Fig. 1b and Extended Data Fig. 1).
The eld-effect mobility was evaluated at weight ratios ranging from 1:9 to 9:1 (DPPT-TT:SHE), as shown in Fig. 1d and Supplementary Figs. 5 and 6.The measured mobility changed only slightly, indicating that the electrical percolation path remained almost intact in lms with DPPT-TT:SHE weight ratios between 9:1 and 3:7.The strain dependency of the semiconducting property was further evaluated through transfer printing of the blend lm (Extended Data Fig. 2 and Supplementary Fig. 7).The eld-effect mobilities of the selectively stretched blend lms on a rigid substrate were measured (Fig. 1e).The blended lm with a weight ratio of 3:7 exhibited the lowest sensitivity toward strain in terms of eld-effect mobility.Optical microscopy (OM) images clearly showed the strain-insensitive nanoweb structure of the 3:7 blended lm, i.e., with no observable cracks even after 30% strain was applied (Fig. 1f and Supplementary Fig. 3).
We used the dichroic ratio to determine the degree of relative DPPT-TT polymer alignment in the blended lms under strain 27 .The dichroic ratio of the 3:7 blend lm increased linearly as the strain was increased to 30% (Fig. 1g and Supplementary Fig. 8), suggesting that the DPPT-TT chains were aligned in the strain direction.To gain further insights into the properties of the 3:7 blend lm, we carried out depth pro ling on three unique points of the lm using X-ray photoelectron spectroscopy (XPS) to analyze the vertical composition distribution.All component distribution (S, Si, and C atoms) in depth of the three points all showed identical trend and the average S and Si atoms were representative of DPPT-TT and SHE, respectively (Fig. 1h and Supplementary Fig. 9) The S signal was evenly distributed throughout the lm thickness, suggesting that DPPT-TT (the only source of S signals) was distributed throughout the lm.This even distribution potentially provided continuous pathways for charge injection and charge transport in the top-contact eld-effect transistor.Si atoms from the self-healing PDMS polymer were found in a higher concentration than S atoms near the surface, indicating that the PDMS polymer may have encapsulated the active channel region at the semiconductor-dielectric interface.The 3:7 blend lm was further analyzed by grazing-incidence X-ray diffraction (GIXD) (Fig. 1i,j and Supplementary Figs. 10 and   11).Its GIXD pattern was almost unchanged under strain as high as 30%, irrespective of the stretching direction.This result suggests that the semiconductor's nanoweb structure helped to release the applied strain and preserved the crystalline domain.This feature is useful to reduce the strain effects on the lm's charge transport properties.

Autonomous self-healing semiconductor
We next conducted self-healing test on the blended lm (weight ratio 3:7) (Fig. 2a).A semiconducting lm on a self-healing dielectric layer was hand cut to have a width of 2.5 µm, a depth of 0.1 µm and a centimeter-scale length via OM images (Fig. 2b, left and Supplementary Fig. 12).The damaged lms were observed to be gradually lled by surrounding materials, leading to complete healing of the damage after 30 h at room temperature (Fig. 2b, right).The microscale damaged areas were characterized by AFM measurements (Fig. 2c-e and Extended Data Fig. 3), and the width of the damaged zone was barely visible after self-healing, while the remaining depth was ~ 10 nm (Fig. 2e, bottom).With a damaged gap width of 4 µm, we observed that the blended lm on dielectric was able to heal the cut (Fig. 2f and Supplementary Figs.13-16).In addition, the scattering pro les before and after healing were almost identical (Supplementary Fig. 17).However, when the damaged gap width was wider, i.e., 5 µm, the damaged region was unable to undergo complete self-repair, but the gap width of the damaged region was reduced by over 50% (from 5 µm to ~ 2 µm) (Supplementary Fig. 18).In case of such larger width of damages, self-healing of the damaged semiconducting lm could be achieved only through posttreatments such as exposure to heat or solvent vapor 11 .These treatments facilitated more movement of the self-healing elastomer, allowing it to ll the damaged gap up to ~ 9 µm and enabling quick reconnection of the DPPT-TT network in the elastomer matrix within 10 min (Supplementary Figs.19-21).
With these results, we next fabricated thin-lm eld-effect transistors with a self-healing semiconducting/dielectric lm on an indium tin oxide (ITO) (gate)/glass rigid substrate (process detailed in Supplementary Fig. 22).The self-healing properties of the semiconducting lm were then evaluated.The transfer curves of the transistors before, during, and after self-healing are shown in Fig. 2g-j.The pristine transistor displayed a typical transfer curve and an average eld-effect mobility of 0.12 cm 2 /(V•s).The semiconductor was again cut in between the source and drain, perpendicular to the current path, using a surgical blade; the damaged gap width was 3 µm, and the depth was 0.1 µm, which is the semiconductor thickness (Fig. 2g and Supplementary Fig. 22a).The damaged device worked again after 12 h, and the mobility gradually increased with increasing healing time.After 3 days, the mobility was restored back akin to an intact device.In addition, the transfer curve of a transistor with a smaller damage width of 1 µm, measured directly after cutting, is shown in Supplementary Fig. 22c.We observed that electrical healing was faster when the damage width is narrower (1 µm vs 3 µm; Fig. 2h).A fast recovery of the transistor characteristics to their initial state was after 12 h.When the current path of the semiconductor was cut in parallel (Supplementary Fig. 22b), autonomous self-healing occurred at similar healing times (Fig. 2i,j and Supplementary Fig. 22d).

Autonomous self-healing electrodes
Self-healing electrodes and dielectrics have been investigated for fully autonomous self-healing transistors 19,[28][29][30] .Here, we used a previously reported stretchable metallization approach for self-healing electrodes, where vaporized Ag atoms form a metal-polymer nanocomposite on the surface of elastic semiconducting and dielectric lms, resulting in robust stretchable electrodes compared to other noble metals (Au and Cu) 24 .In addition, the native oxide of Ag (Ag x O) with high work function (Φ W = 5.2 eV) in the nanocomposite allows good contact with DPPT-TT semiconductor (HOMO level = 5.04 eV) for stretchable transistors 24 .To verify the compatibility of Ag metallization for self-healing transistors, we evaluated the self-healing performance of the Ag metallized self-healing semiconductor (as source/drain electrodes) and self-healing substrate (as a gate electrode).The Ag-supramolecular polymer nanocomposite was con rmed by XPS depth pro ling (Fig. 3a), and the Ag x O was observed in the nanocomposite (Fig. 3b,c).Consequently, the effective Schottky barrier height for current injection was below 0.1 eV (Fig. 3d and Supplementary Fig. 23) 24,31 .Figure .3e shows the variations in resistance of the Ag-metallized self-healing gate electrode under strain.The initial resistance of the Ag gate electrode was 13 Ω (Ag thickness: 80 nm).The resistance of the Ag electrode on the SHE lms was found to be stable under biaxial strain as high as 30% and remained < 100 Ω after 100 cycles under 30% biaxial strain, based on nano-crack damages (Fig. 3f and Extended Data Fig. 4a,c).The self-healing property of the electrode was investigated though changes in the electrode resistance with different damage size as a function of self-healing time (Fig. 3g).After the electrodes were cut, the resistance of the electrode with a 3 µm damage width increased dramatically to the 10 7 Ω level, mostly electrically disconnected.However, the resistance recovered after 1 day and almost reached its original value after 80 h.The rapid initial selfhealing process is attributed to the elastic recovery of the supramolecular elastomer near the damaged area.However, it is followed by a slower electrical recovery (after 40 h), which may be due to surface rearrangement and diffusion of the polymer chains 32,33 .For the narrower damage width at 1 µm, the resistance was initially reduced to the 10 2 Ω level and fully recovered to its initial value after 24 h.Additionally, the cutting lines in the optical images of the cut electrode almost disappeared after 24 h (Fig. 3h and Supplementary Figs.24 and 25).The reconstruction of the Ag electrodes was attributed mainly to the metal-polymer nanocomposite region composed of thermally evaporated Ag nanoclusters and mobile chains of the supramolecular polymer on the surface of the SHE lm (Extended Data Fig. 5) 19,24,30 .The Ag metallization applied to the self-healing semiconductor layer also showed a stable resistance (Fig. 3i) and remained mechanically robust even when subjected to 30% biaxial strain for 100 cycles (Fig. 3j and Extended Data Fig. 4b,d).The initial resistance of the Ag electrode on the semiconducting lms was 10 1 Ω.However, when the lms were cut, the resistance increased dramatically to 10 2 Ω and 10 4 Ω for both damage widths of 1 µm and 3 µm, respectively.However, the damaged Ag/semiconductor lm was recovered through the reconstruction of the metal-polymer nanocomposite and the semiconductor lm.As a result, the resistance of Ag metallized layer recovered after 36 h (Fig. 3k) and the cutting line almost disappeared for both cutting widths with increasing self-healing time (Fig. 3l and Supplementary Figs. 26 and 27).The self-healed Ag/SHE and Ag/semiconductor lms could be stretched again to 30% strain without electrical disconnection (Extended Data Fig. 6).Moreover, the metal-polymer nanocomposite layer functions as a physical glue at the interfaces (Ag/SHE and Ag/semiconductor), providing strong adhesion at the interfaces and thereby improving the mechanical robustness of the electrodes.The electrodes almost maintained their electrical resistance even after several peel-off tests using 3M tape (Supplementary Fig. 28).

Autonomous self-healing dielectric and transistors
The self-healing capability of the dielectric layer is another critical aspect of fully stretchable self-healing transistors 34 .The supramolecular elastomer (PDMS-MPU0 0.6 -IU 0.4 ) was used as the stretchable and self-healing dielectric in a metal-insulator-metal (MIM) con guration of Ag/dielectric/Ag (Supplementary Fig. 29).In transistors, the dielectric strength of the gate dielectric plays a critical role in preventing electrical breakdown 35 .This self-healing dielectric (thickness: 1.5 µm) with smooth surface (roughness: < 1 nm) exhibited a breakdown voltage of 170 V at a current density of 10 − 7 A/cm 2 (Fig. 4a and Supplementary Fig. 30).In addition, the dielectric exhibited a consistent capacitance value in the investigated frequency range (10 2 -10 5 Hz) with − 20 V to 20 V (Fig. 4b) 36 ; the dielectric constant (k) was 7.2.Under a biaxial strain as high as 30%, the dielectric capacitance slightly increased across the entire investigated frequency range (Fig. 4c). 37With a decrease in the dielectric thickness due to biaxial strain, the corresponding capacitance (C i ) values of the MIM capacitors at 10 3 Hz increased from 1.74 nF/cm 2 (pristine, 0%) to 2.24 nF/cm 2 (30% biaxial strain) without any physical defects (Supplementary Fig. 30).
To demonstrate the self-healing ability of the dielectric layer, damage with a width of 3 µm and length of a few centimeters was induced on the dielectric using a surgical blade and the healing time was monitored.Figure 4d shows the capacitance and dielectric constant values of the dielectric in its pristine and post-healing states (Extended Data Fig. 7).
Based on the above results, the self-healing semiconductor, conductor, and dielectric materials were successfully integrated into a single transistor device and passive arrays of 5 × 5 self-healing transistors were fabricated (Supplementary Fig. 31). Figure . 4e shows typical transfer curves for 25 devices in a transistor array with a low leakage current and an on/off ratio greater than 10 4 .Typical output curves of the device without s-shape were shown, which indicates good electrical contacts at the source/drain and semiconductor interfaces (Supplementary Fig. 32a) 24,38 .Additionally, all unit devices in the arrays exhibited uniform saturation mobility values (average of 25 devices: 0.11 ± 0.02 cm 2 /V•s) (Supplementary Fig. 32b) and three batches of the array (n = 3) showed a similar trend (Supplementary Fig. 32c).
For stretchability, we tested the devices under both uniaxial and biaxial strains.The cyclic strain-stress curve of the transistor array (Supplementary Fig. 33) for the strains ranging from 10-100% showed that the device can be stretched without permanent plastic deformations.All devices maintained their initial mobility and on-current under uniaxial and biaxial strains as high as 30% (Fig. 4f and Supplementary Figs.34-37).Changes in the capacitances of the stretchable self-healing dielectrics and device geometries according to the applied strain are summarized in Supplementary Table 1.
To evaluate the self-healing e ciency, we rst cut all components within the transistor array (width: 4 µm and depth: 2 µm) using a surgical blade in both directions parallel and perpendicular to the electrical pathways (i.e., forming a cross shape between the transistors), and then proceed to monitor their performance and structural recovery over time.As expected, the transistors showed complete disconnection of the pathway immediately after the array was cut.However, all the transistors were able to autonomously self-heal over time (duration dependent on cut severity), and eventually restored most of their original mobilities and morphology (Fig. 4g,h, Extended Data Fig. 8 and Supplementary Fig. 38).This represents the rst report that all layers in the polymer transistor are fully stretchable and autonomous self-healing (Supplementary Table 2).The healing time was observed to be the same regardless of the cut directions.Furthermore, all the transistors demonstrated > 77% recovery e ciency (average mobility: 0.07 ± 0.02 cm 2 /V•s, with a maximum of 0.09 cm 2 /V•s).Interestingly, our stretchable self-healing transistors in the array exhibited excellent ambient stability with and without encapsulation for up to one month (Extended Data Fig. 9a,b).We attributed the stability of the electrodes in air to self-encapsulation by supramolecular polymer in the semiconducting blend lm (Fig. 1h and Extended Data Fig. 9c,d).

Self-healable skin electronics
Last, we demonstrate the self-healing active-matrix arrays (Fig. 5a,b and Supplementary Fig. 39).The pristine array exhibited a uniform on-current in 25 devices, with a narrow deviation (Fig. 5c); different batches (n = 3) showed similar uniformity (Supplementary Fig. 40).The typical transfer and output characteristics of the representative unit device (Fig. 5d) showed low gate currents and operation at low voltage (− 1 V D ).They maintained the initial on-currents under biaxial strain as high as 30% (Fig. 5e and Supplementary Fig. 41).Conductive-AFM images showed the current mapping of the active region of the semiconducting lm at 30% biaxial and uniaxial strains (Fig. 5f and Supplementary Fig. 42).The nanoweb-structured self-healing semiconductor was evenly stretched uniaxially and biaxially without electrical disconnections.This observation is direct evidence that the semiconducting lm maintained the electrical percolation path under a biaxial strain (30%) and is suitable for applications on dynamic soft surfaces, such as human skin or organs.In addition, the array was tested for cross-shaped damage by deep cutting with a surgical blade to simulate harsh damage conditions.After 48 h, the typical electrical properties of all the damaged locations were restored, as demonstrated by the recovered on-current shown in Fig. 5g and Supplementary Fig. 43.The C-AFM image in Fig. 5h shows obvious reconnections of the conduction pathways after healing.
To demonstrate practical applications for our self-healing supramolecular polymer transistors, we prepared autonomously self-healable and stretchable inverters, NAND gates, and NOR gates, which are basic building blocks of digital integrated circuits (Fig. 5i-n and Supplementary Figs.44 and 45).The pristine inverter exhibited a typical voltage transfer curve (VTC) with a gain of 3, depending on the V IN and V OUT values, enabling 2-bit calculation.The VTC performance was similar to that of the pristine transistors under biaxial strain as high as 30% (Fig. 5l, top-right; Supplementary Figs.46 and 47).For selfhealing experiments, the inverter exhibited similar performance as the pristine device after cut and heal at room temperature for 40 h, displaying negligible variation (Fig. 5l, bottom; Supplementary Fig. 48).In addition, the self-healed inverter was capable of stretching under biaxial strain as high as 30% without electrical disconnection (Extended Data Fig. 10a,b).
NAND and NOR gates were also fabricated with the self-healing transistors (Fig. 5j,k and Supplementary Figs.49 and 50).For output characteristics of the NAND and NOR devices (Fig. 5m,n, Supplementary Figs.51-54) in their pristine state, V OUT exhibits a certain value according to the logic table and a similar trend under biaxial strain (Fig. 5m,n, top-right).When the two-drive transistor suffered damage (Supplementary Figs.55 and 56), the V OUT value became zero (Fig. 5m,n, bottom-left).After autonomous self-healing, V OUT returned to its original value (Fig. 5m,n, bottom-right), and the healed logic gates could stretch up to 30% biaxial strain again (Extended Data Fig. 10c,d).

Conclusion
We demonstrated autonomous self-healing transistors and circuit elements consisting of identical supramolecular polymer-based electronic components for skin electronics.Nanoweb-structured semiconductor network and stretchable metallization were developed for autonomous self-healing stretchable semiconductor and electrodes (source/drain and gate), respectively.In addition, the insulating high-k supramolecular elastomer was used for the low operating voltage of the transistor.The transistors showed strain-insensitive electrical properties even after autonomous self-healing.With the autonomous self-healing transistors, we successfully fabricated active-matrix array and logic gates that are fundamental building blocks of digital system.These results would pave the way for the skin electronics based on integrated circuits with self-healing functional systems.
After reaction, MeOH (5 mL) was added and stirred for 30 minutes to remove the remained isocyanate.Then, the solution was concentrated to ½ of its volume.18 mL MeOH was poured into the mixture solution to give a viscous liquid.After settling for 30 minutes, the upper clear solution was then decanted.30 mL CHCl 3 was added to dissolve the product.The dissolution-precipitation-decantation process was repeated three times for purifying and the nal product was subjected in ambient condition to remove the solvent and trace of Et 3 N.

Rigid substrate-based thin lm
The semiconductor solution prepared by dissolving both DPPT-TT (0.21 wt%) and SHE (0.49 wt%) with a total of 0.7 wt%, in anhydrous chloroform at 50 °C for 4 hours.The solution was spun on an OTStreated SiO 2 /Si wafer at 1000 rpm for 1 min after ltration with a PTFE-D (0.2 μm) lter ( lm thickness: 100 nm).The semiconducting lm was then annealed at 80 ℃ for 30 min.All of above processes were carried out under an N 2 atmosphere in a glove box with extremely low levels of moisture (H 2 O < 0.01 parts per million (ppm)) and oxygen (O 2 < 0.01 ppm).
The SHE dielectric solution (60 mg/mL in chloroform) was spun at 2000 rpm for 1 min ( lm thickness: 1.5 μm), without any heat treatment, onto an indium tin oxide (ITO) glass substrate with a sheet resistance of 20 ohm/square.The semiconducting lm was transferred onto the SHE dielectric using a PDMS stamp.The silver source/drain electrodes were then evaporated at a rate of 0.2 nm/s using a thermal evaporator.The channel length and width were set at 1000 and 150 μm, respectively.For calculation of effective Schottky barrier height, the transistor device was measured with structure (Ag/semiconductor/SiO 2 /Si) in vacuum state.
Fully stretchable and self-healing transistors: The SHE substrate solution was spin-coated onto an OTS-treated SiO 2 /Si wafer using the SHE solution (50 mg/mL in chloroform) at 2000 rpm for 1 minute without any heat treatment.The resulting SHE substrate was transferred onto the SEBS substrate to be stretchability and elasticity.An 80 nm thick Ag gate electrode was evaporated onto the SHE substrate at a speed of 0.2 nm/s under high vacuum conditions (below 5.0×10 -6 torr).Next, the SHE dielectric (60 mg/ml, 2000 rpm for 1 minute on OTStreated SiO 2 ) and semiconducting lm (in a 3:7 ratio of DPPT-TT and SHE) were sequentially transferred onto the gate electrode.Finally, 80 nm thick Ag source/drain electrodes were evaporated onto the semiconducting lms.

Active-matrix transistor
All the procedures were identical to the fabrication process of fully stretchable and autonomous selfhealing transistors, except for the dielectric lm.For the dielectric lm, a different concentration (80 mg/ml in chloroform, 2.1 μm thickness) was used to reduce leakage current, and it was spin-coated at 1000 rpm for 1 minute to achieve a thicker dielectric lm.

Logic gate devices including inverter, NAND, NOR:
The self-healing substrate, semiconducting thin-lm, and dielectric layer were prepared using the same process as the fully stretchable and self-healing active-matrix transistor array.Bottom Ag electrodes (80 nm) were evaporated onto the self-healing substrates, each designed for speci c logic gates.The semiconducting lms and dielectric layer were then transferred onto the Ag electrode in sequence.Finally, the top Ag electrodes (80 nm) were thermally evaporated following the designed pattern.

Characterization
The electrical characteristics of the devices were measured using a four probe (MCP-T610) and probe station connected with KEITHLEY 4200 under ambient conditions.The capacitances of the dielectric were measured using a probe station connected with an LCR meter (Keysight 4274A).The strain-stress curve was obtained by a force tester (AND, MCT-2150; strain rate: 100 mm/min).For cutting process, a surgical blade (Feather, No.25) was used.UV-Vis-Nir spectra were obtained with a spectrophotometer (JASCO, V-770).Surface structures, and current images were obtained with atomic force microscopy (AFM; Bruker MultiMode 8-HR) under ambient conditions.DMT modulus mappings were measured using PeakForce quantitative nanoscale mechanical (QNM) AFM.Optical images were obtained with an optical microscope (OM; Leica DM4 M).The thicknesses of the lm were obtained with an ellipsometer (WONWOO STRC-2000).Grazing incidence X-ray diffraction (GIXD) patterns of self-healing semiconducting thin lms were performed on a laboratory beamline system (Xenocs Inc.Xeuss 2.0) with an X-ray wavelength of 1.54 Å and a sample-to-detector distance of 15 cm and the incidence angle of 0.2 ˚.Samples were kept under vacuum to minimize air scattering.Diffraction images were recorded on a Pilatus 1M detector (Dectris Inc.) with an exposure time of 1.5 h and processed using the Nika software package, in combination with WAXSTolls in Igor Pro.X-ray photoelectron spectra depth pro ling was obtained with XPS equipment (Thermo Electron, K-Alpha).Surface energy and contact angle were obtained by PHOENIX-MT(T).

Figures
Figure 1 Material design of autonomous self-healing a, Schematic of an autonomous self-healing semiconducting lm, featuring the chemical structure of a self-healing elastomer (PDMS-MPU 0.6 -IU 0.4 ) and a semiconducting polymer (DPPT-TT).b, AFM analysis of the 3:7 (DPPT-TT:SHE) blend ratio lm: (i) height, (ii) phase, (iii) DMT modulus, and (iv) C-AFM images.c, Elastic modulus and onset strains of cracks in the lms with different blend ratios of self-healing semiconductor.d, Field-effect mobilities of blend lms as a function of the blend weight ratio (DPPT-TT:SHE).e, Field-effect mobility ratios of the blend lms as a function of the blend weight ratio and tensile strain.f, OM images of the 3:7 blend ratio lm at 0% (left) and 100% strain (right).g, Dichroic ratio from polarized UV-Vis-NIR spectra at each tensile strain.h, XPS spectra of the 3:7 blend lm.GIXD of the 3:7 blend lm under 0% and 30% strain, where the strained lm was stretched parallel and perpendicular to the beam line.i, out-of-plane and j, inplane lm direction.All error bars were calculated using a sample in each of three batches (n = 3).

Figure 5 Self
Figure 5