resources involves the conversion of sunlight energy directly to electricity using photovoltaic technologies. In this regard, extensive research efforts are being been focused on the development of new photovoltaic devices, including organic solar cells (OSCs), perovskite solar cells (PVSCs), and organic light-emitting diodes (OLEDs). [1,2] Such devices benefit from the numerous advantages of organic compounds, which can be chemically modified to achieve the desired device performance. [3][4][5][6] With decades of study, organic semiconductors now exhibit outstanding electronic and structural properties that has led to the fabrication of innovative organic devices with impressive output characteristics, including high field-effect mobility (10 cm 2 V −1 s −1 ) in organic field-effect transistors (OFETs), and high efficiencies of 17% in OSCs and 25% in PVSCs. [7][8][9][10][11][12][13][14][15] Furthermore, the inexpensive access of organic materials that can be processed through low-cost solution processing methods is widely attractive for practical applications that require the light-weight devices to be flexible and transparent. [16] The performance of organic electronic devices depends primarily on the properties of the active layer and electrodes, but also relies heavily on the properties of the various device interfaces. In recent years, a remarkable advancement in device Compared to their inorganic counterparts, organic optoelectronic devices receive considerable attention due to their lower cost, mechanical flexibility, bandgap engineering, and solution processability. In particular, achieving sustainability in solar cells and light emitting devices is an important milestone in the development of green electronics. This has facilitated a close collaboration between different technological fields, opening new ways for low-cost production and application of biomaterials. Recently, biomass materials, mainly derived from plants, animals and microorganisms, have emerged as effective candidates to modify the interfacial properties, and thus enhance the performance, lifetime, and stability of organic solar cells (OSCs), perovskite solar cells (PVSCs), and organic light-emitting diodes (OLEDs). Compared to the commonly used synthetic interfacial materials, the use of biomass interlayer materials (BIMs) is still in its embryonic stages; however, their nontoxicity, biorelevance, sustainability, special proton conductivity, and rich functional groups are stimulating researchers around the globe to fabricate novel devices with improved efficiency. Herein, a comprehensive review of BIMs and their importance in next-generation optoelectronic devices is provided. A welltargeted comparison between the electrical and physical properties of different BIMs is provided, and how such characteristics improve the performance of three key optoelectronic devices: OSCs, PVSCs and OLEDs, is discussed.