Accelerating the shift towards renewable materials and sustainable processes for printed organic electronic devices is crucial for a green circular economy. Currently, the fabrication of organic devices with competitive performances is linked to toxic petrochemical-based solvents with considerable carbon emissions. Here we show that terpene solvents obtained from renewable feedstocks can replace non-renewable environmentally hazardous solvent counterparts in the production of highly efficient organic photovoltaics (OPVs) light-emitting diodes (OLEDs) and field-effect transistors (OFETs) with on-par performances. Using a Hansen solubility ink formulation framework, we identify various terpene solvent systems and investigate effective film formation and drying mechanisms required for optimal charge transport. This approach is universal for state-of-the-art materials in OPVs, OLEDs and OFETs. We created an interactive library for green solvent selections and made it publicly available through the OMEGALab website. As potential carbon-negative solvents, terpenes open a unique and universal approach towards efficient, large-area and stable organic electronic devices.

With the advent of halide perovskites, a large number of electronic and optoelectronic devices have been demonstrated with exceptional performance, the most notable being solar cells. [1-3] The facile and cost-effective fabrication of perovskites, coupled with their multifunctional nature, makes them a viable material for future practical devices. Recently, the application of halide perovskites has been extended to thermoelectrics due to their ultralow thermal conductivity. Thermoelectric efficiency is defined by the dimensionless figure of merit, ZT where ZT ¼ σS 2 T/κ, and σ, S, T and κ are the electrical conductivity, Seebeck coefficient, absolute temperature, and thermal conductivity of the thermoelectric material, respectively. Minimizing the thermal conductivity and maximizing the power factor (PF) (defined as σS 2) is the general route of achieving high ZT. Although almost all halide perovskites exhibit ultralow thermal conductivity, the electrical conductivity has a huge variation depending on the metal cation. Lead (Pb)based perovskites have high Seebeck coefficient but very low electrical conductivity limiting their thermoelectric prospects. [4,5] On the other hand, Sn perovskites have high electrical conductivity arising from the oxidative nature of Sn 2þ. [6-8] Although this high conductivity is unfavorable for solar cells, it could be beneficial for thermoelectric applications. In fact, so far the best thermoelectric performance achieved in the case of emerging halide perovskite-based thermoelectrics is for inorganic Sn-perovskites. [9-11] Cesium tin halides, CsSnX 3 (X: halide) are continuously being pursued for thermoelectrics as they exhibit good electrical conductivity and ultralow thermal conductivity. To this end, hybrid Sn and binary Sn-Pb perovskites have received limited attention. Also, theoretical works have predicted methylammonium tin iodide (CH 3 NH 3 SnI 3) as a promising thermoelectric material. [12,13] Previous works probing the electrical conductivity and Seebeck of CH 3 NH 3 SnI 3 used single crystals or polycrystalline pellets as sample. [6,14,15] It is crucial to understand the transport behavior of CH 3 NH 3 SnI 3 in the form of thin films for facile device integration. In addition, the time scales and degree of oxidation leading to the observed metal-like behavior in Sn-perovskites constitutes an important issue. [15,16] In context to solar cells, a number of strategies have been used to stabilize Sn-perovskites such as the addition of SnF 2 , metallic Sn, ZnI 2 , and organic materials to mitigate the high carrier density which leads to solar cell failure. [17-20] So, understanding the oxidative behavior of Sn perovskites and control over it will be beneficial for thermoelectrics as well as solar cell research. In this work, a systematic study on the p doping of CH 3 NH 3 SnI 3 and Sn-Pb binary hybrid perovskite, CH 3 NH 3 Sn 0.75 Pb 0.25 I 3 due to air exposure is accomplished to tune their thermoelectric properties. A correlation between electronic stability and air exposure ...

Doping serves as a vital strategy for tuning electronic and optoelectronic properties of semiconductors. Compared to organic semiconductors, the understanding and optimization of the doping process in halide perovskite semiconductors is still in its infancy. Nonetheless, there is a continuous surge in doping these semiconductors for performance enhancement. This perspective discusses the central role of dopants in organic and halide perovskite-based semiconductors used for energy conversion devices, particularly solar cells and thermoelectrics. We summarize various p-and n-type dopants explored for modifying the active layer in organic and perovskite devices, highlighting their challenges and limitations. Understanding doping-induced changes in electronic properties and their ramifications on device performance is essential for improving the device performance.

Tin–lead perovskite solar cells (TLPSCs) have emerged as one of the most efficient photovoltaic technologies. However, their stability under operational conditions (ambient air, temperature, bias, and illumination) is lagging behind their sharp efficiency increase, restraining their further development. In this Focus Review, we provide insights into the degradation mechanisms of tin–lead perovskites and summarize the principal factors that currently limit the operational stability of TLPSCs. Specifically, perovskite composition and the device architecture stand out as critical aspects governing their sensitivity toward stressors such as temperature and light. We discuss several strategies to overcome these limitations and emphasize the adoption of standardized methods to quantify the lifetime of a device. We further propose using various characterization techniques to identify possible device failure mechanisms. We expect this Focus Review to assist in the progress toward the development of efficient and stable perovskite devices.

The efficiency of tin-lead perovskite solar cells (TLPSC) has been consistently increasing. However, their photostability continues to be a persistent challenge. Besides the oxidation of tin (Sn), the presence of...