Recent progress on performance-enhancing strategies in flexible photodetectors: From structural engineering to flexible integration

As an important component of future electronic devices, photodetectors require mechanical flexibility, and stretchability to meet the demands of conformal, portable, and lightweight applications. As expected, flexible photodetectors (FPDs) were born timely and have obtained rapid development driven by the considerable progress of the optoelectronic industry. Especially, FPDs appear to serve as a bridge between electronic information systems and biological systems due to their potential functional applications including wearable devices, artificial intelligence, bionics devices, etc. However, the poor mechanical stability, narrow spectral response range, low responsivities and difficulty in miniaturization of traditional FPDs have greatly limited their commercial and industrial applications. One of the most promising routes toward addressing the inherent shortcomings of FPDs is through constructing novel micro/nano-structured integrated flexible detection systems to achieve diverse functions and enhance performance, hence facilitating flexible integration. In this review, the recent advances in performance-enhancing strategies for FPDs are outlined and discussed. First, the detection mechanism, performance enhancement mode, and key figures-of-merit of FPDs are summarized and basic design principles of the FPDs are discussed emphatically. Then, recent progress in structural engineering-based performance enhancement of FPDs is reviewed, categorized by the types of enhancement, electric field manipulation engineering, strain engineering, and optical field manipulation engineering. Moreover, this review also summarizes the integration strategies for the application of FPDs and finally puts forward the challenges and future research directions in these fields.