Transparent Supercapacitors: From Optical Theories to Optoelectronics Applications

The ever-increasing demand for smart optoelectronics spurs the relentless pursuit of transparent wireless devices as a game-changing technology that can provide unseen visual information behind the electronics. To enable successful operation of the transparent wireless devices, their power sources should be highly transparent in addition to acquiring reliable electrochemical performance. Among various transparent power sources, supercapacitors (SCs) have been extensively investigated as a promising candidate due to their exceptional cyclability, power capability, material diversity, and scalable/low-cost processability. Herein, we describe current status and challenges of transparent SCs, with a focus on their core materials, performance advancements, and integration with application devices. A special attention is devoted to transparent conductive electrodes (TCEs) which act as a key-enabling component in the transparent SCs. Based on fundamental understanding of optical theories and operating principles of transparent materials, we comprehensively discuss materials chemistry, structural design, and fabrication techniques of TCEs. In addition, noteworthy progresses of transparent SCs are briefly overviewed in terms of their architectural design, opto-electrochemical performance, flexibility, form factors, and integration compatibility with transparent flexible/wearable devices of interest. Finally, development direction and outlook of transparent SCs are explored along with their viable roles in future application fields