| dc.description.abstract | The absorbers of Tin Perovskite solar cells (TPSCs) have great prospects due to their ideal energy gap (∼1.4 eV) and low toxicity. The power conversion efficiency (PCE) has achieved a significantly value of 15%. However, the tin perovskite absorber is susceptible to Sn2+ oxidation and rapid crystallization, leading to problems such as poor stability, and poor film quality. Moreover, the cell may have poor interfacial compatibility between carrier transporting layer and tin perovskite layer. Lots of researches focus on adding additives to the tin perovskite precursor solution to inhibit the oxidation of Sn2+, but less studies focus on the issue of interfacial compatibility. In this study, we used a published polymer PDTON as a base, using the same isopropyl-triphenylamine (i-pr-TPA) with hole transport ability as the Acceptor. The hole-transporting moiety cyclopentadithiophene (CPDT) with two hydrophilic alkylamine side chains was used (instead of TPA on PDTON) as a donor to prepared a new bipolar polymer PTSN. There are three advantages of PTSN: First, it uses the hole-extracting thiophene in the CPDT structure to extract effectively the holes from the tin perovskite layer. The second is that compared to TPA, CPDT has two hydrophilic alkylamine chain can better modify the surface and HOMO energy of the hole transport layer (HTL) Cu-SnCo2O4 (Cu-SCO) to match better the valence band of the tin perovskite and the Lewis base amine group can passivate the defects of the tin perovskite film. The third is that PTSN has both hydrophilic and hydrophobic groups, which can increase the affinity between the tin perovskite precursor and PTSN. The thermal decomposition temperatures of both polymers are greater than 200°C. UV-Vis absorption spectra show that at the same concentration, the light absorption of the PTSN solution and film is smaller than those of PDTON, allowing more photons to reach the tin perovskite absorber. Contact angle of the tin perovskite precursor solution on PTSN film is smaller than that on the PDTON film, indicating that the compatibility with tin perovskite precursor solution is better. Moreover, the valence band edge (-5.53) of the Cu-SCO/PTSN film better matched with the valence band (-5.74 eV) of the tin perovskite than that (-5.49) of Cu-SCO/PDTON film therefore the energy loss of hole transporting is less. FTIR spectra show that the C-N stretching of amine and C-S stretching of thiophene of PTSN+SnI2 and PTSN+Cu-SCO both blue-shifted compared to pure PTSN, indicating that the lone pairs of nitrogen on the amine group and sulfur on thiophene could interact with the coordinated unsaturated Sn2+ of Cu-SCO film and tin perovskite surface. PL and TRPL data show that the fluorescence intensity of tin perovskite deposited on PTSN-modified Cu-SCO is weaker than that deposited on Cu-SCO/PDTON and Cu-SCO HTLs, and the carrier lifetime is also shorter, indicating that Cu- SCO/PTSN HTL can most effectively extract the holes from tin perovskite. The PCE of inverted TPSCs using polymer PTSN as the interface modification layer can reach 9.30% (compared to 8.06% for using PDTON as a interface modificate agent and 7.91% for cell coithout interface modification agent). | en_US |