Exploiting coordination between poly (ethylene glycol) bis (carboxymethyl) ether and SnO2 for high-performance perovskite photodetectors

In perovskite detectors that utilize SnO2 as an electron transport layer (ETL), the preparation of SnO2 films using the solution method results in a significant number of defects. Additionally, the presence of nano-aggregates in the aqueous solution of untreated SnO2 colloids leads to surface unevenness in SnO2 films prepared using the spin-coating method, which can affect the growth and crystallization of perovskite. Defects and surface unevenness in SnO2 films affect the performance of perovskite detectors. To further optimize the performance of perovskite detectors, SnO2 incorporating poly (ethylene glycol) bis (carboxymethyl) ether (PBE) was developed, employing the polymer as a modifier. The results of the study showed that the incorporation of PBE had two effects: 1) the ether oxygen within the PBE forms a coordination bond with SnO2, thereby reducing oxygen vacancies, and 2) reducing nano-aggregation of SnO2 colloidal aqueous solutions, obtaining more uniform SnO2 films, and promoting the growth and crystallization of perovskite. Ultimately, the performance of the optimized device was improved. The external quantum efficiency (EQE) improved from 84.82 % to 89.29 %, the dark current density decreased from 3.27 x 10-9 A cm-2 to 1.03 x 10-10 A cm-2, the linear dynamic range (LDR) increased from 88.5 to 118.3 dB, and the stability was enhanced. The device maintained 64.9 % of its original efficiency after being stored for 23 days at 25 degrees C and 20-30 % humidity.